Antigen-binding proteins that activate the leptin receptor

ABSTRACT

The present invention provides antibodies and antigen-binding fragments of antibodies that bind to leptin receptor (LEPR), and methods of using the same. According to certain embodiments, the invention includes antibodies and antigen-binding fragments of antibodies that bind LEPR and activate LEPR signaling. In other embodiments, the invention includes antibodies and antigen-binding fragments of antibodies that bind to LEPR and enhance sensitization of LEPR to an antigen. In certain embodiments, the invention includes antibodies and antigen-binding fragments of antibodies that bind LEPR in the presence and absence of leptin. In certain embodiments, the invention includes antibodies and antigen-binding fragments of antibodies that induce signaling in cells expressing LEPR mutants that otherwise exhibit defective or impaired signaling in the presence of leptin. The antibodies and antigen-binding fragments of the present invention are useful for the treatment of lipodystrophies and other diseases and disorders associated with or caused by leptin deficiency or leptin resistance.

This application claims the benefit of priority under 35 U.S.C. §119(e)of U.S. provisional application Nos. 62/240,021, filed Oct. 12, 2015,62/359,757, filed Jul. 8, 2016, 62/375,495, filed Aug. 16, 2016 and62/393,143, filed Sep. 12, 2016, the disclosures of which are hereinincorporated by reference in their entireties.

SEQUENCE LISTING

An official copy of the sequence listing is submitted concurrently withthe specification electronically via EFS-Web as an ASCII formattedsequence listing with a file name of2016_10_11_10178US01_Sequence_Listing_as_Filed_ST25.TXT, a creation dateof Oct. 11, 2016, and a size of about 99.7 kilobytes. The sequencelisting contained in this ASCII formatted document is part of thespecification and is herein incorporated by reference in its entirety.

FIELD OF INVENTION

The present invention is related to antibodies and antigen-bindingfragments of antibodies that bind human leptin receptor (LEPR), andtherapeutic and diagnostic methods of using those antibodies.

BACKGROUND

Leptin is a polypeptide hormone predominantly expressed by adiposetissue and is involved in the regulation of metabolism, energy balanceand food intake. Leptin activity is mediated by interaction with, andsignaling through, the leptin receptor. Leptin receptor, (also known as“LEPR,” “WSX,” “OB receptor,” “OB-R,” and “CD295”) is a single-passtransmembrane receptor of the class I cytokine receptor family with alarge (818 amino acid) extracellular domain. Leptin deficiency, leptinresistance, and certain LEPR signaling-defective/signaling impairedmutations, are associated with obesity, type 2 diabetes, dyslipidemia,lipodystrophies, hepatic steatosis, non-alcoholic and alcoholic fattyliver diseases, severe insulin resistance, Leprechaunism/Donohuesyndrome, Rabson-Mendenhall syndrome, and related complications.Therapeutic approaches to address leptin resistance, leptin deficiency,and hypoleptinemia (e.g., lipodystrophy) have mostly focused on thedelivery of supplemental leptin or leptin analogues to affectedindividuals. Such approaches, however, have generally shown limitedefficacy, particularly in leptin-resistant individuals, and arefrequently associated with adverse side effects. Thus, a need exists inthe art for alternative approaches to treating leptin resistance andother conditions associated with leptin deficiency or hypoleptinemia.

BRIEF SUMMARY OF THE INVENTION

The present invention provides antibodies and antigen-binding fragmentsthereof that bind human leptin receptor (LEPR). The antibodies of thepresent invention are agonist antibodies; i.e., binding of the anti-LEPRantibodies of the invention to LEPR causes, inter alia, activation ofleptin receptor signaling in cells. In certain embodiments, theantibodies of the present invention do not compete with leptin forbinding to LEPR. The antibodies of the present invention are useful,e.g., for mimicking, substituting for, or supplementing the normalbiological activity of leptin in a subject. The antibodies andantigen-binding fragments of the present invention are therefore usefulin the therapeutic treatment of diseases and disorders associated withleptin resistance and leptin deficiency.

The antibodies of the invention can be full-length (for example, an IgG1or IgG4 antibody) or may comprise only an antigen-binding portion (forexample, a Fab, F(ab′)₂ or scFv fragment), and may be modified to affectfunctionality, e.g., to eliminate residual effector functions (Reddy etal., 2000, J. Immunol. 164:1925-1933).

Exemplary anti-LEPR antibodies of the present invention are listed inTables 1 and 2 herein. Table 1 sets forth the amino acid sequenceidentifiers of the heavy chain variable regions (HCVRs), light chainvariable regions (LCVRs), heavy chain complementarity determiningregions (HCDR1, HCDR2 and HCDR3), and light chain complementaritydetermining regions (LCDR1, LCDR2 and LCDR3) of the exemplary anti-LEPRantibodies. Table 2 sets forth the nucleic acid sequence identifiers ofthe HCVRs, LCVRs, HCDR1, HCDR2 HCDR3, LCDR1, LCDR2 and LCDR3 of theexemplary anti-LEPR antibodies.

The present invention provides antibodies or antigen-binding fragmentsthereof that specifically bind LEPR, comprising an HCVR comprising anamino acid sequence selected from any of the HCVR amino acid sequenceslisted in Table 1, or a substantially similar sequence thereof having atleast 90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising an LCVRcomprising an amino acid sequence selected from any of the LCVR aminoacid sequences listed in Table 1, or a substantially similar sequencethereof having at least 90%, at least 95%, at least 98% or at least 99%sequence identity thereto.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising an HCVR and anLCVR amino acid sequence pair (HCVR/LCVR) comprising any of the HCVRamino acid sequences listed in Table 1 paired with any of the LCVR aminoacid sequences listed in Table 1. According to certain embodiments, thepresent invention provides antibodies, or antigen-binding fragmentsthereof, comprising an HCVR/LCVR amino acid sequence pair containedwithin any of the exemplary anti-LEPR antibodies listed in Table 1. Incertain embodiments, the HCVR/LCVR amino acid sequence pair is selectedfrom the group consisting of SEQ ID NOs: 2/10, 18/10, 26/10, 34/10,42/10, 50/10, 58/66, 74/66 and 82/66.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising a heavy chainCDR1 (HCDR1) comprising an amino acid sequence selected from any of theHCDR1 amino acid sequences listed in Table 1 or a substantially similarsequence thereof having at least 90%, at least 95%, at least 98% or atleast 99% sequence identity.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising a heavy chainCDR2 (HCDR2) comprising an amino acid sequence selected from any of theHCDR2 amino acid sequences listed in Table 1 or a substantially similarsequence thereof having at least 90%, at least 95%, at least 98% or atleast 99% sequence identity.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising a heavy chainCDR3 (HCDR3) comprising an amino acid sequence selected from any of theHCDR3 amino acid sequences listed in Table 1 or a substantially similarsequence thereof having at least 90%, at least 95%, at least 98% or atleast 99% sequence identity.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising a light chainCDR1 (LCDR1) comprising an amino acid sequence selected from any of theLCDR1 amino acid sequences listed in Table 1 or a substantially similarsequence thereof having at least 90%, at least 95%, at least 98% or atleast 99% sequence identity.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising a light chainCDR2 (LCDR2) comprising an amino acid sequence selected from any of theLCDR2 amino acid sequences listed in Table 1 or a substantially similarsequence thereof having at least 90%, at least 95%, at least 98% or atleast 99% sequence identity.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising a light chainCDR3 (LCDR3) comprising an amino acid sequence selected from any of theLCDR3 amino acid sequences listed in Table 1 or a substantially similarsequence thereof having at least 90%, at least 95%, at least 98% or atleast 99% sequence identity.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising an HCDR3 andan LCDR3 amino acid sequence pair (HCDR3/LCDR3) comprising any of theHCDR3 amino acid sequences listed in Table 1 paired with any of theLCDR3 amino acid sequences listed in Table 1. According to certainembodiments, the present invention provides antibodies, orantigen-binding fragments thereof, comprising an HCDR3/LCDR3 amino acidsequence pair contained within any of the exemplary anti-LEPR antibodieslisted in Table 1. In certain embodiments, the HCDR3/LCDR3 amino acidsequence pair is selected from the group consisting of SEQ ID NOs: 8/16,24/16, 32/16, 40/16, 48/16, 56/16, 64/72, 80/72 and 88/72.

The present invention also provides antibodies or antigen-bindingfragments thereof that specifically bind LEPR, comprising a set of sixCDRs (i.e., HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3) containedwithin any of the exemplary anti-LEPR antibodies listed in Table 1. Incertain embodiments, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3amino acid sequences set is selected from the group consisting of SEQ IDNOs: 4, 6, 8, 12, 14, 16; 20, 22, 24, 12, 14, 16; 28, 30, 32, 12, 14,16; 36, 38, 40, 12, 14, 16; 44, 46, 48, 12, 14, 16; 52, 54, 56, 12, 14,16; 60, 62, 64, 68, 70, 72; 76, 78, 80, 68, 70, 72; and 84, 86, 88, 68,70, 72.

In a related embodiment, the present invention provides antibodies, orantigen-binding fragments thereof that specifically bind LEPR,comprising a set of six CDRs (i.e., HCDR1, HCDR2, HCDR3, LCDR1, LCDR2,and LCDR3) contained within an HCVR/LCVR amino acid sequence pair asdefined by any of the exemplary anti-LEPR antibodies listed in Table 1.For example, the present invention includes antibodies orantigen-binding fragments thereof that specifically bind LEPR,comprising the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 amino acidsequences set contained within an HCVR/LCVR amino acid sequence pairselected from the group consisting of SEQ ID NOs: 2/10, 18/10, 26/10,34/10, 42/10, 50/10, 58/66, 74/66 and 82/66. Methods and techniques foridentifying CDRs within HCVR and LCVR amino acid sequences are wellknown in the art and can be used to identify CDRs within the specifiedHCVR and/or LCVR amino acid sequences disclosed herein. Exemplaryconventions that can be used to identify the boundaries of CDRs include,e.g., the Kabat definition, the Chothia definition, and the AbMdefinition. In general terms, the Kabat definition is based on sequencevariability, the Chothia definition is based on the location of thestructural loop regions, and the AbM definition is a compromise betweenthe Kabat and Chothia approaches. See, e.g., Kabat, “Sequences ofProteins of Immunological Interest,” National Institutes of Health,Bethesda, Md. (1991); Al-Lazikani et al., J. Mol. Biol. 273:927-948(1997); and Martin et al., Proc. Natl. Acad. Sci. USA 86:9268-9272(1989). Public databases are also available for identifying CDRsequences within an antibody.

The present invention also provides nucleic acid molecules encodinganti-LEPR antibodies or portions thereof. For example, the presentinvention provides nucleic acid molecules encoding any of the HCVR aminoacid sequences listed in Table 1; in certain embodiments the nucleicacid molecule comprises a polynucleotide sequence selected from any ofthe HCVR nucleic acid sequences listed in Table 2, or a substantiallysimilar sequence thereof having at least 90%, at least 95%, at least 98%or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding anyof the LCVR amino acid sequences listed in Table 1; in certainembodiments the nucleic acid molecule comprises a polynucleotidesequence selected from any of the LCVR nucleic acid sequences listed inTable 2, or a substantially similar sequence thereof having at least90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides nucleic acid molecules encoding anyof the HCDR1 amino acid sequences listed in Table 1; in certainembodiments the nucleic acid molecule comprises a polynucleotidesequence selected from any of the HCDR1 nucleic acid sequences listed inTable 2, or a substantially similar sequence thereof having at least90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides nucleic acid molecules encoding anyof the HCDR2 amino acid sequences listed in Table 1; in certainembodiments the nucleic acid molecule comprises a polynucleotidesequence selected from any of the HCDR2 nucleic acid sequences listed inTable 2, or a substantially similar sequence thereof having at least90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides nucleic acid molecules encoding anyof the HCDR3 amino acid sequences listed in Table 1; in certainembodiments the nucleic acid molecule comprises a polynucleotidesequence selected from any of the HCDR3 nucleic acid sequences listed inTable 2, or a substantially similar sequence thereof having at least90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides nucleic acid molecules encoding anyof the LCDR1 amino acid sequences listed in Table 1; in certainembodiments the nucleic acid molecule comprises a polynucleotidesequence selected from any of the LCDR1 nucleic acid sequences listed inTable 2, or a substantially similar sequence thereof having at least90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides nucleic acid molecules encoding anyof the LCDR2 amino acid sequences listed in Table 1; in certainembodiments the nucleic acid molecule comprises a polynucleotidesequence selected from any of the LCDR2 nucleic acid sequences listed inTable 2, or a substantially similar sequence thereof having at least90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides nucleic acid molecules encoding anyof the LCDR3 amino acid sequences listed in Table 1; in certainembodiments the nucleic acid molecule comprises a polynucleotidesequence selected from any of the LCDR3 nucleic acid sequences listed inTable 2, or a substantially similar sequence thereof having at least90%, at least 95%, at least 98% or at least 99% sequence identitythereto.

The present invention also provides nucleic acid molecules encoding anHCVR, wherein the HCVR comprises a set of three CDRs (i.e., HCDR1,HCDR2, HCDR3), wherein the HCDR1, HCDR2, HCDR3 amino acid sequence setis as defined by any of the exemplary anti-LEPR antibodies listed inTable 1.

The present invention also provides nucleic acid molecules encoding anLCVR, wherein the LCVR comprises a set of three CDRs (i.e., LCDR1,LCDR2, LCDR3), wherein the LCDR1, LCDR2, LCDR3 amino acid sequence setis as defined by any of the exemplary anti-LEPR antibodies listed inTable 1.

The present invention also provides nucleic acid molecules encoding bothan HCVR and an LCVR, wherein the HCVR comprises an amino acid sequenceof any of the HCVR amino acid sequences listed in Table 1, and whereinthe LCVR comprises an amino acid sequence of any of the LCVR amino acidsequences listed in Table 1. In certain embodiments, the nucleic acidmolecule comprises a polynucleotide sequence selected from any of theHCVR nucleic acid sequences listed in Table 2, or a substantiallysimilar sequence thereof having at least 90%, at least 95%, at least 98%or at least 99% sequence identity thereto, and a polynucleotide sequenceselected from any of the LCVR nucleic acid sequences listed in Table 2,or a substantially similar sequence thereof having at least 90%, atleast 95%, at least 98% or at least 99% sequence identity thereto. Incertain embodiments according to this aspect of the invention, thenucleic acid molecule encodes an HCVR and LCVR, wherein the HCVR andLCVR are both derived from the same anti-LEPR antibody listed in Table1.

The present invention also provides recombinant expression vectorscapable of expressing a polypeptide comprising a heavy or light chainvariable region of an anti-LEPR antibody. For example, the presentinvention includes recombinant expression vectors comprising any of thenucleic acid molecules mentioned above, i.e., nucleic acid moleculesencoding any of the HCVR, LCVR, and/or CDR sequences as set forth inTable 1. Also included within the scope of the present invention arehost cells into which such vectors have been introduced, as well asmethods of producing the antibodies or portions thereof by culturing thehost cells under conditions permitting production of the antibodies orantibody fragments, and recovering the antibodies and antibody fragmentsso produced.

In another aspect, the invention provides a pharmaceutical compositioncomprising a recombinant human antibody or fragment thereof whichspecifically binds LEPR and a pharmaceutically acceptable carrier. In arelated aspect, the invention features a composition which is acombination of an anti-LEPR antibody and a second therapeutic agent. Inone embodiment, the second therapeutic agent is any agent that isadvantageously combined with an anti-LEPR antibody.

In yet another aspect, the invention provides therapeutic methods forenhancing or stimulating LEPR signaling using an anti-LEPR antibody orantigen-binding portion of an antibody of the invention. The therapeuticmethods according to this aspect of the invention comprise administeringa therapeutically effective amount of a pharmaceutical compositioncomprising an antibody or antigen-binding fragment of an antibody of theinvention to a subject in need thereof. The disorder treated is anydisease or condition which is improved, ameliorated, inhibited orprevented by stimulating or activating LEPR signaling, or otherwisemimicking the natural activity of leptin in vitro or in vivo.

Other embodiments will become apparent from a review of the ensuingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts the binding of dimeric human LEPR to human Leptin in thepresence of increasing concentrations of test anti-LEPR antibodies orcontrol molecules, as measured by ELISA (absorbance at 450 nm).

FIGS. 2A-2C illustrates the extent of LEPR signaling in HEK293 cellsexpressing either wild-type LEPR (circles), a signaling-defective LEPRmutant (A409E, squares), or a signaling-impaired LEPR mutant (P316T,triangles). LEPR signaling is expressed as ratio of pSTAT3-Y705/STAT3,measured by densitometry from Western blots prepared from cells treatedwith increasing concentrations of leptin (FIG. 2A), H4H16650 (FIG. 2B),or H4H16679 (FIG. 2C).

FIG. 3 shows the average daily food intake of leptin-deficient micedosed with either an isotype control antibody at 3 mg/kg, or a LEPRantibody selected from H4H16650P2, H4H16679P2, H4H17319P2 or H4H17321P2at 3 mg/kg.

FIG. 4 shows the average percent change in body weight of mice dosedwith either an isotype control antibody at 3 mg/kg, or a LEPR antibodyselected from H4H16650P2, H4H16679P2, H4H17319P2 or H4H17321P2 at 3mg/kg.

FIG. 5 shows the average fat mass for animals in each antibody treatmentgroup quantified by μCT 1 day prior to (bars not shaded) and 6 daysfollowing antibody treatment (shaded bars) expressed as mean±SEM.

FIG. 6 shows the percent change in body weight of mice fed 30 mg/kg ofan antibody selected from H4H18482P2, H4H18487P2, H4H18492P2 or anisotype control.

FIGS. 7A-7B. FIG. 7A shows the fat mass of mice before dosing withanti-LEPR antibodies H4H18482P2, H4H18487P2 or H4H18492P2. FIG. 7B showsthe fat mass of mice treated with 30 mg/kg of H4H18482P2, H4H18487P2 orH4H18492P2.

FIG. 8. FIG. 8 shows that anti-LEPR antibodies tested activated monkey(Mf) LEPR in an IMR-32/STAT3-luc/Mf LEPR cell line.

DETAILED DESCRIPTION OF THE INVENTION

Before the present invention is described, it is to be understood thatthis invention is not limited to particular methods and experimentalconditions described, as such methods and conditions may vary. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting, since the scope of the present invention will be limitedonly by the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. As used herein, the term“about,” when used in reference to a particular recited numerical value,means that the value may vary from the recited value by no more than 1%.For example, as used herein, the expression “about 100” includes 99 and101 and all values in between (e.g., 99.1, 99.2, 99.3, 99.4, etc.).

Although any methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of the presentinvention, the preferred methods and materials are now described. Allpatents, applications and non-patent publications mentioned in thisspecification are incorporated herein by reference in their entireties.

Definitions

The expression “leptin receptor,” “LEPR,” and the like, as used herein,refers to the human leptin receptor, comprising the amino acid sequenceas set forth in SEQ ID NO:113 (see also UniProtKB/Swiss-Prot AccessionNo. P48357). Alternative names for LEPR used in the scientificliterature include “OB receptor,” “OB-R,” and “CD295.” LEPR is alsoreferred to as “WSX” (see, e.g., U.S. Pat. No. 7,524,937). Theexpression “LEPR” includes both monomeric and multimeric (e.g., dimeric)LEPR molecules. As used herein, the expression “monomeric human LEPR”means a LEPR protein or portion thereof that does not contain or possessany multimerizing domains and that exists under normal conditions as asingle LEPR molecule without a direct physical connection to anotherLEPR molecule. An exemplary monomeric LEPR molecule is the moleculereferred to herein as “hLEPR.mmh” comprising the amino acid sequence ofSEQ ID NO:114 (see, e.g., Example 3, herein). As used herein, theexpression “dimeric human LEPR” means a construct comprising two LEPRmolecules connected to one another through a linker, covalent bond,non-covalent bond, or through a multimerizing domain such as an antibodyFc domain. An exemplary dimeric LEPR molecule is the molecule referredto herein as “hLEPR.mFc” comprising the amino acid sequence of SEQ IDNO:115 (see, e.g., Example 3, herein), or the molecule referred toherein as “hLEPR.hFc” comprising the amino acid sequence of SEQ IDNO:116. As used herein, expressions such “anti-LEPR antibody,” “antibodythat specifically binds LEPR,” “LEPR-specific binding protein,” and thelike, unless specifically indicated otherwise, refer to molecules thatbind full length human LEPR, monomeric human LEPR, dimeric human LEPR,or other constructs that comprise or consist of the LEPR extracellulardomain.

All references to proteins, polypeptides and protein fragments hereinare intended to refer to the human version of the respective protein,polypeptide or protein fragment unless explicitly specified as beingfrom a non-human species. Thus, the expression “LEPR” means human LEPRunless specified as being from a non-human species, e.g., “mouse LEPR,”“monkey LEPR,” etc.

As used herein, the expression “cell surface-expressed LEPR” means oneor more LEPR protein(s), or the extracellular domain thereof, thatis/are expressed on the surface of a cell in vitro or in vivo, such thatat least a portion of a LEPR protein is exposed to the extracellularside of the cell membrane and is accessible to an antigen-bindingportion of an antibody. A “cell surface-expressed LEPR” can comprise orconsist of a LEPR protein expressed on the surface of a cell whichnormally (e.g., in the native or wild-type state) expresses LEPRprotein. Alternatively, “cell surface-expressed LEPR” can comprise orconsist of LEPR protein expressed on the surface of a cell that normallydoes not express human LEPR on its surface but has been artificiallyengineered to express LEPR on its surface.

As used herein, the expressions such as “anti-LEPR antibody,” or“antibody that binds human leptin receptor,” include both monovalentantibodies with a single specificity, as well as bispecific antibodiescomprising a first arm that binds LEPR and a second arm that binds asecond (target) antigen, wherein the anti-LEPR arm comprises any of theHCVR/LCVR or CDR sequences as set forth in Table 1 herein.

The term “antibody”, as used herein, means any antigen-binding moleculeor molecular complex comprising at least one complementarity determiningregion (CDR) that specifically binds to or interacts with a particularantigen (e.g., LEPR). The term “antibody” includes immunoglobulinmolecules comprising four polypeptide chains, two heavy (H) chains andtwo light (L) chains inter-connected by disulfide bonds, as well asmultimers thereof (e.g., IgM). Each heavy chain comprises a heavy chainvariable region (abbreviated herein as HCVR or V_(H)) and a heavy chainconstant region. The heavy chain constant region comprises threedomains, C_(H)1, C_(H)2 and C_(H)3. Each light chain comprises a lightchain variable region (abbreviated herein as LCVR or V_(L)) and a lightchain constant region. The light chain constant region comprises onedomain (C_(L)1). The V_(H) and V_(L) regions can be further subdividedinto regions of hypervariability, termed complementarity determiningregions (CDRs), interspersed with regions that are more conserved,termed framework regions (FR). Each V_(H) and V_(L) is composed of threeCDRs and four FRs, arranged from amino-terminus to carboxy-terminus inthe following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. In differentembodiments of the invention, the FRs of the anti-LEPR antibody (orantigen-binding portion thereof) may be identical to the human germlinesequences, or may be naturally or artificially modified. An amino acidconsensus sequence may be defined based on a side-by-side analysis oftwo or more CDRs.

The term “antibody”, as used herein, also includes antigen-bindingfragments of full antibody molecules. The terms “antigen-bindingportion” of an antibody, “antigen-binding fragment” of an antibody, andthe like, as used herein, include any naturally occurring, enzymaticallyobtainable, synthetic, or genetically engineered polypeptide orglycoprotein that specifically binds an antigen to form a complex.Antigen-binding fragments of an antibody may be derived, e.g., from fullantibody molecules using any suitable standard techniques such asproteolytic digestion or recombinant genetic engineering techniquesinvolving the manipulation and expression of DNA encoding antibodyvariable and optionally constant domains. Such DNA is known and/or isreadily available from, e.g., commercial sources, DNA libraries(including, e.g., phage-antibody libraries), or can be synthesized. TheDNA may be sequenced and manipulated chemically or by using molecularbiology techniques, for example, to arrange one or more variable and/orconstant domains into a suitable configuration, or to introduce codons,create cysteine residues, modify, add or delete amino acids, etc.

Non-limiting examples of antigen-binding fragments include: (i) Fabfragments; (ii) F(ab′)2 fragments; (iii) Fd fragments; (iv) Fvfragments; (v) single-chain Fv (scFv) molecules; (vi) dAb fragments; and(vii) minimal recognition units consisting of the amino acid residuesthat mimic the hypervariable region of an antibody (e.g., an isolatedcomplementarity determining region (CDR) such as a CDR3 peptide), or aconstrained FR3-CDR3-FR4 peptide. Other engineered molecules, such asdomain-specific antibodies, single domain antibodies, domain-deletedantibodies, chimeric antibodies, CDR-grafted antibodies, diabodies,triabodies, tetrabodies, minibodies, nanobodies (e.g. monovalentnanobodies, bivalent nanobodies, etc.), small modularimmunopharmaceuticals (SMIPs), and shark variable IgNAR domains, arealso encompassed within the expression “antigen-binding fragment,” asused herein.

An antigen-binding fragment of an antibody will typically comprise atleast one variable domain. The variable domain may be of any size oramino acid composition and will generally comprise at least one CDRwhich is adjacent to or in frame with one or more framework sequences.In antigen-binding fragments having a V_(H) domain associated with aV_(L) domain, the V_(H) and V_(L) domains may be situated relative toone another in any suitable arrangement. For example, the variableregion may be dimeric and contain V_(H)-V_(H), V_(H)-V_(L) orV_(L)-V_(L) dimers. Alternatively, the antigen-binding fragment of anantibody may contain a monomeric V_(H) or V_(L) domain.

In certain embodiments, an antigen-binding fragment of an antibody maycontain at least one variable domain covalently linked to at least oneconstant domain. Non-limiting, exemplary configurations of variable andconstant domains that may be found within an antigen-binding fragment ofan antibody of the present invention include: (i) V_(H)-C_(H)1; (ii)V_(H)-C_(H)2; (iii) V_(H)-C_(H)3; (iv) V_(H)-C_(H)1-C_(H)2; (v)V_(H)-C_(H)1-C_(H)2-C_(H)3; (vi) V_(H)-C_(H)2-C_(H)3; (vii) V_(H)-C_(L);(viii) V_(L)-C_(H)1; (ix) V_(L)-C_(H)2; (x) V_(L)-C_(H)3; (xi)V_(L)-C_(H)1-C_(H)2; (xii) V_(L)-C_(H)1-C_(H)2-C_(H)3; (xiii)V_(L)-C_(H)2-C_(H)3; and (xiv) V_(L)-C_(L). In any configuration ofvariable and constant domains, including any of the exemplaryconfigurations listed above, the variable and constant domains may beeither directly linked to one another or may be linked by a full orpartial hinge or linker region. A hinge region may consist of at least 2(e.g., 5, 10, 15, 20, 40, 60 or more) amino acids which result in aflexible or semi-flexible linkage between adjacent variable and/orconstant domains in a single polypeptide molecule. Moreover, anantigen-binding fragment of an antibody of the present invention maycomprise a homo-dimer or hetero-dimer (or other multimer) of any of thevariable and constant domain configurations listed above in non-covalentassociation with one another and/or with one or more monomeric V_(H) orV_(L) domain (e.g., by disulfide bond(s)).

As with full antibody molecules, antigen-binding fragments may bemonospecific or multispecific (e.g., bispecific). A multispecificantigen-binding fragment of an antibody will typically comprise at leasttwo different variable domains, wherein each variable domain is capableof specifically binding to a separate antigen or to a different epitopeon the same antigen. Any multispecific antibody format, including theexemplary bispecific antibody formats disclosed herein, may be adaptedfor use in the context of an antigen-binding fragment of an antibody ofthe present invention using routine techniques available in the art.

In certain embodiments of the invention, the anti-LEPR antibodies of theinvention are human antibodies. The term “human antibody”, as usedherein, is intended to include antibodies having variable and constantregions derived from human germline immunoglobulin sequences. The humanantibodies of the invention may include amino acid residues not encodedby human germline immunoglobulin sequences (e.g., mutations introducedby random or site-specific mutagenesis in vitro or by somatic mutationin vivo), for example in the CDRs and in particular CDR3. However, theterm “human antibody”, as used herein, is not intended to includeantibodies in which CDR sequences derived from the germline of anothermammalian species, such as a mouse, have been grafted onto humanframework sequences.

The antibodies of the invention may, in some embodiments, be recombinanthuman antibodies. The term “recombinant human antibody”, as used herein,is intended to include all human antibodies that are prepared,expressed, created or isolated by recombinant means, such as antibodiesexpressed using a recombinant expression vector transfected into a hostcell (described further below), antibodies isolated from a recombinant,combinatorial human antibody library (described further below),antibodies isolated from an animal (e.g., a mouse) that is transgenicfor human immunoglobulin genes (see e.g., Taylor et al. (1992) Nucl.Acids Res. 20:6287-6295) or antibodies prepared, expressed, created orisolated by any other means that involves splicing of humanimmunoglobulin gene sequences to other DNA sequences. Such recombinanthuman antibodies have variable and constant regions derived from humangermline immunoglobulin sequences. In certain embodiments, however, suchrecombinant human antibodies are subjected to in vitro mutagenesis (or,when an animal transgenic for human Ig sequences is used, in vivosomatic mutagenesis) and thus the amino acid sequences of the V_(H) andV_(L) regions of the recombinant antibodies are sequences that, whilederived from and related to human germline V_(H) and V_(L) sequences,may not naturally exist within the human antibody germline repertoire invivo.

The present invention encompasses antibodies having one or moremutations in the hinge, C_(H)2 or C_(H)3 region which may be desirable,for example, in production, to improve the yield of the desired antibodyform.

The antibodies of the invention may be isolated antibodies. An “isolatedantibody,” as used herein, means an antibody that has been identifiedand separated and/or recovered from at least one component of itsnatural environment. For example, an antibody that has been separated orremoved from at least one component of an organism, or from a tissue orcell in which the antibody naturally exists or is naturally produced, isan “isolated antibody” for purposes of the present invention. Anisolated antibody also includes an antibody in situ within a recombinantcell. Isolated antibodies are antibodies that have been subjected to atleast one purification or isolation step. According to certainembodiments, an isolated antibody may be substantially free of othercellular material and/or chemicals.

The present invention includes variants of the anti-LEPR antibodiesdisclosed herein comprising one or more amino acid substitutions,insertions and/or deletions in the framework and/or CDR regions of theheavy and light chain variable domains as compared to the correspondinggermline sequences from which the antibodies were derived. Suchmutations can be readily ascertained by comparing the amino acidsequences disclosed herein to germline sequences available from, forexample, public antibody sequence databases. The present inventionincludes antibodies, and antigen-binding fragments thereof, which arederived from any of the amino acid sequences disclosed herein, whereinone or more amino acids within one or more framework and/or CDR regionsare mutated to the corresponding residue(s) of the germline sequencefrom which the antibody was derived, or to the corresponding residue(s)of another human germline sequence, or to a conservative amino acidsubstitution of the corresponding germline residue(s) (such sequencechanges are referred to herein collectively as “germline mutations”). Aperson of ordinary skill in the art, starting with the heavy and lightchain variable region sequences disclosed herein, can easily producenumerous antibodies and antigen-binding fragments which comprise one ormore individual germline mutations or combinations thereof. In certainembodiments, all of the framework and/or CDR residues within the V_(H)and/or V_(L) domains are mutated back to the residues found in theoriginal germline sequence from which the antibody was derived. In otherembodiments, only certain residues are mutated back to the originalgermline sequence, e.g., only the mutated residues found within thefirst 8 amino acids of FR1 or within the last 8 amino acids of FR4, oronly the mutated residues found within CDR1, CDR2 or CDR3. In otherembodiments, one or more of the framework and/or CDR residue(s) aremutated to the corresponding residue(s) of a different germline sequence(i.e., a germline sequence that is different from the germline sequencefrom which the antibody was originally derived). Furthermore, theantibodies of the present invention may contain any combination of twoor more germline mutations within the framework and/or CDR regions,e.g., wherein certain individual residues are mutated to thecorresponding residue of a particular germline sequence while certainother residues that differ from the original germline sequence aremaintained or are mutated to the corresponding residue of a differentgermline sequence. Once obtained, antibodies and antigen-bindingfragments that contain one or more germline mutations can be easilytested for one or more desired property such as, improved bindingspecificity, increased binding affinity, improved or enhancedantagonistic or agonistic biological properties (as the case may be),reduced immunogenicity, etc. Antibodies and antigen-binding fragmentsobtained in this general manner are encompassed within the presentinvention.

The present invention includes anti-LEPR antibodies and antigen-bindingfragments thereof that comprise amino acid sequences that aresubstantially similar or substantially identical to one or more variabledomain or CDR amino acid sequences as found in any of the exemplaryanti-LEPR antibodies disclosed herein.

As applied to polypeptides, the term “substantial similarity” or“substantially similar” means that two peptide sequences, when optimallyaligned, such as by the programs GAP or BESTFIT using default gapweights, share at least 95% sequence identity, even more preferably atleast 98% or 99% sequence identity. Preferably, residue positions whichare not identical differ by conservative amino acid substitutions. A“conservative amino acid substitution” is one in which an amino acidresidue is substituted by another amino acid residue having a side chain(R group) with similar chemical properties (e.g., charge orhydrophobicity). In general, a conservative amino acid substitution willnot substantially change the functional properties of a protein. Incases where two or more amino acid sequences differ from each other byconservative substitutions, the percent sequence identity or degree ofsimilarity may be adjusted upwards to correct for the conservativenature of the substitution. Means for making this adjustment arewell-known to those of skill in the art. See, e.g., Pearson (1994)Methods Mol. Biol. 24: 307-331, herein incorporated by reference.Examples of groups of amino acids that have side chains with similarchemical properties include (1) aliphatic side chains: glycine, alanine,valine, leucine and isoleucine; (2) aliphatic-hydroxyl side chains:serine and threonine; (3) amide-containing side chains: asparagine andglutamine; (4) aromatic side chains: phenylalanine, tyrosine, andtryptophan; (5) basic side chains: lysine, arginine, and histidine; (6)acidic side chains: aspartate and glutamate, and (7) sulfur-containingside chains are cysteine and methionine. Preferred conservative aminoacids substitution groups are: valine-leucine-isoleucine,phenylalanine-tyrosine, lysine-arginine, alanine-valine,glutamate-aspartate, and asparagine-glutamine. Alternatively, aconservative replacement is any change having a positive value in thePAM250 log-likelihood matrix disclosed in Gonnet et al. (1992) Science256: 1443-1445, herein incorporated by reference. A “moderatelyconservative” replacement is any change having a nonnegative value inthe PAM250 log-likelihood matrix.

Sequence similarity for polypeptides, which is also referred to assequence identity, is typically measured using sequence analysissoftware. Protein analysis software matches similar sequences usingmeasures of similarity assigned to various substitutions, deletions andother modifications, including conservative amino acid substitutions.For instance, GCG software contains programs such as Gap and Bestfitwhich can be used with default parameters to determine sequence homologyor sequence identity between closely related polypeptides, such ashomologous polypeptides from different species of organisms or between awild type protein and a mutein thereof. See, e.g., GCG Version 6.1.Polypeptide sequences also can be compared using FASTA using default orrecommended parameters, a program in GCG Version 6.1. FASTA (e.g.,FASTA2 and FASTA3) provides alignments and percent sequence identity ofthe regions of the best overlap between the query and search sequences(Pearson (2000) supra). Another preferred algorithm when comparing asequence of the invention to a database containing a large number ofsequences from different organisms is the computer program BLAST,especially BLASTP or TBLASTN, using default parameters. See, e.g.,Altschul et al. (1990) J. Mol. Biol. 215:403-410 and Altschul et al.(1997) Nucleic Acids Res. 25:3389-402, each herein incorporated byreference.

Anti-LEPR Antibodies Comprising Fc Variants

According to certain embodiments of the present invention, anti-LEPRantibodies are provided comprising an Fc domain comprising one or moremutations which enhance or diminish antibody binding to the FcRnreceptor, e.g., at acidic pH as compared to neutral pH. For example, thepresent invention includes anti-LEPR antibodies comprising a mutation inthe C_(H)2 or a C_(H)3 region of the Fc domain, wherein the mutation(s)increases the affinity of the Fc domain to FcRn in an acidic environment(e.g., in an endosome where pH ranges from about 5.5 to about 6.0). Suchmutations may result in an increase in serum half-life of the antibodywhen administered to an animal. Non-limiting examples of such Fcmodifications include, e.g., a modification at position 250 (e.g., E orQ); 250 and 428 (e.g., L or F); 252 (e.g., L/Y/F/W or T), 254 (e.g., Sor T), and 256 (e.g., S/R/Q/E/D or T); or a modification at position 428and/or 433 (e.g., H/L/R/S/P/Q or K) and/or 434 (e.g., H/F or Y); or amodification at position 250 and/or 428; or a modification at position307 or 308 (e.g., 308F, V308F), and 434. In one embodiment, themodification comprises a 428L (e.g., M428L) and 434S (e.g., N434S)modification; a 428L, 259 I(e.g., V259I), and 308F (e.g., V308F)modification; a 433K (e.g., H433K) and a 434 (e.g., 434Y) modification;a 252, 254, and 256 (e.g., 252Y, 254T, and 256E) modification; a 250Qand 428L modification (e.g., T250Q and M428L); and a 307 and/or 308modification (e.g., 308F or 308P).

For example, the present invention includes anti-LEPR antibodiescomprising an Fc domain comprising one or more pairs or groups ofmutations selected from the group consisting of: 250Q and 248L (e.g.,T250Q and M248L); 252Y, 254T and 256E (e.g., M252Y, S254T and T256E);428L and 434S (e.g., M428L and N434S); and 433K and 434F (e.g., H433Kand N434F). All possible combinations of the foregoing Fc domainmutations, and other mutations within the antibody variable domainsdisclosed herein, are contemplated within the scope of the presentinvention.

The anti-LEPR antibodies of the present invention may comprise amodified Fc domain having reduced effector function. As used herein, a“modified Fc domain having reduced effector function” means any Fcportion of an immunoglobulin that has been modified, mutated, truncated,etc., relative to a wild-type, naturally occurring Fc domain such that amolecule comprising the modified Fc exhibits a reduction in the severityor extent of at least one effect selected from the group consisting ofcell killing (e.g., ADCC and/or CDC), complement activation,phagocytosis and opsonization, relative to a comparator moleculecomprising the wild-type, naturally occurring version of the Fc portion.In certain embodiments, a “modified Fc domain having reduced effectorfunction” is an Fc domain with reduced or attenuated binding to an Fcreceptor (e.g., FcγR).

In certain embodiments of the present invention, the modified Fc domainis a variant IgG1 Fc or a variant IgG4 Fc comprising a substitution inthe hinge region. For example, a modified Fc for use in the context ofthe present invention may comprise a variant IgG1 Fc wherein at leastone amino acid of the IgG1 Fc hinge region is replaced with thecorresponding amino acid from the IgG2 Fc hinge region. Alternatively, amodified Fc for use in the context of the present invention may comprisea variant IgG4 Fc wherein at least one amino acid of the IgG4 Fc hingeregion is replaced with the corresponding amino acid from the IgG2 Fchinge region. Non-limiting, exemplary modified Fc regions that can beused in the context of the present invention are set forth in US PatentApplication Publication No. 2014/0243504, the disclosure of which ishereby incorporated by reference in its entirety, as well as anyfunctionally equivalent variants of the modified Fc regions set forththerein.

Other modified Fc domains and Fc modifications that can be used in thecontext of the present invention include any of the modifications as setforth in US 2014/0171623; U.S. Pat. No. 8,697,396; US 2014/0134162; WO2014/043361, the disclosures of which are hereby incorporated byreference in their entireties. Methods of constructing antibodies orother antigen-binding fusion proteins comprising a modified Fc domain asdescribed herein are known in the art.

Biological Characteristics of the Antibodies

The present invention includes antibodies and antigen-binding fragmentsthereof that bind human LEPR and activate LEPR signaling. Suchantibodies may be referred to herein as “agonist antibodies.” In thecontext of the present invention, “activation of LEPR signaling” meansthe stimulation of an intracellular effect that normally results fromthe interaction of leptin with LEPR in cells that express LEPR. Incertain embodiments, “activation of LEPR signaling” means thetranscriptional activation of STAT3, which can be detected using anymethod that can measure or identify, directly or indirectly, STAT3activity, e.g., using a labeled version of STAT3 expressed in a reportercell line. For example, the present invention includes antibodies andantigen-binding fragments thereof that activate LEPR signaling in acell-based reporter assay, e.g., using a cell based assay format asdefined in Example 7 herein, or a substantially similar assay.Cell-based reporter assays that detect LEPR activation, such as theassay set forth in Example 7 herein, can produce a detectable signalthat may be expressed in terms of an EC₅₀ value (i.e., the antibodyconcentration required to produce half-maximal signaling) and/or apercentage of the maximal signaling observed in the presence of leptin.In certain exemplary embodiments of the present invention, anti-LEPRantibodies are provided that activate LEPR signaling with an EC₅₀ valueof less than about 12.0 nM in a cell-based reporter assay, e.g., usingan assay format as defined in Example 7 herein, or a substantiallysimilar assay. In certain exemplary embodiments of the presentinvention, anti-LEPR antibodies are provided that activate LEPRsignaling with maximum percent activation relative to leptin signalingof greater than about 65% in a cell-based reporter assay, e.g., using anassay format as defined in Example 7 herein, or a substantially similarassay.

The present invention includes antibodies and antigen-binding fragmentsthereof that bind monomeric human LEPR with high affinity. For example,the present invention includes anti-LEPR antibodies that bind monomerichuman LEPR (e.g., hLEPR.mmh, SEQ ID NO:114) with a K_(D) of less thanabout 150 nM as measured by surface plasmon resonance at 25° C. or 37°C., e.g., using an assay format as defined in Example 3 herein, or asubstantially similar assay. According to certain embodiments, anti-LEPRantibodies are provided that bind monomeric human LEPR at 25° C. with aK_(D) of less than about 150 nM, less than about 140 nM, less than about130 nM, less than about 120 nM, less than about 110 nM, less than about100 nM, less than about 90 nM, less than about 80 nM, less than about 70nM, less than about 60 nM, less than about 50 nM, less than about 40 nM,less than about 30 nM, less than about 20 nM, less than about 10 nM,less than about 9 nM, less than about 8 nM, less than about 7 nM, lessthan about 6 nM, less than about 5 nM, less than about 4 nM, less thanabout 3 nM, less than about 2 nM, less than about 1 nM, less than about900 pM, less than about 800 pM, less than about 700 pM, less than about600 pM, less than about 500 pM, less than about 400 pM, or less thanabout 300 pM, as measured by surface plasmon resonance, e.g., using anassay format as defined in Example 3 herein, or a substantially similarassay.

The present invention also includes antibodies and antigen-bindingfragments thereof that bind monomeric human LEPR (e.g., hLEPR.mmh, SEQID NO:114) with a dissociative half-life (t½) of greater than about 50minutes as measured by surface plasmon resonance at 25° C. or 37° C.,e.g., using an assay format as defined in Example 3 herein, or asubstantially similar assay. According to certain embodiments, anti-LEPRantibodies are provided that bind monomeric human LEPR at 25° C. with at½ of greater than about 50 minutes, greater than about 55 minutes,greater than about 60 minutes, greater than about 65 minutes, or longer,as measured by surface plasmon resonance, e.g., using an assay format asdefined in Example 3 herein, or a substantially similar assay.

The present invention also includes antibodies and antigen-bindingfragments thereof that bind dimeric human LEPR (e.g., hLEPR.mFc, SEQ IDNO:115) with high affinity. For example, the present invention includesanti-LEPR antibodies that bind dimeric human LEPR with a K_(D) of lessthan about 1.5 nM as measured by surface plasmon resonance at 25° C. or37° C., e.g., using an assay format as defined in Example 3 herein, or asubstantially similar assay. According to certain embodiments, anti-LEPRantibodies are provided that bind dimeric human LEPR at 25° C. with aK_(D) of less than about 150 nM, less than about 130 nM, less than about110 nM, less than about 80 nM, less than about 70 nM, less than about 60nM, less than about 50 nM, less than about 40 nM, less than about 30 nM,less than about 20 nM, or less than about 10 nM, as measured by surfaceplasmon resonance, e.g., using an assay format as defined in Example 3herein, or a substantially similar assay.

The present invention also includes antibodies and antigen-bindingfragments thereof that bind dimeric human LEPR (e.g., hLEPR.mFc, SEQ IDNO:115) with a dissociative half-life (t½) of greater than about 10minutes as measured by surface plasmon resonance at 25° C. or 37° C.,e.g., using an assay format as defined in Example 3 herein, or asubstantially similar assay. According to certain embodiments, anti-LEPRantibodies are provided that bind dimeric human LEPR at 25° C. with a t½of greater than about 10, greater than about 15 minutes, greater thanabout 20 minutes, greater than about 25 minutes, greater than about 30minutes, greater than about 40 minutes, greater than about 50 minutes,greater than about 60 minutes, greater than about 70 minutes, or longer,as measured by surface plasmon resonance, e.g., using an assay format asdefined in Example 3 herein, or a substantially similar assay.

The present invention also includes antibodies and antigen-bindingfragments thereof that bind LEPR in complex with human leptin (“LEPR incomplex with human leptin” may also be represented by the expression“leptin:LEPR”). For example the present invention includes antibodiesand antigen-binding fragments thereof that are capable of binding to apre-formed complex comprising hLEPR and human leptin. That is, accordingto certain embodiments, the interaction between anti-LEPR antibodies andLEPR is not inhibited by the presence of leptin in complex with LEPR;likewise, the interaction between leptin and LEPR, according to thisaspect of the invention, is not inhibited by the presence of ananti-LEPR antibody. An exemplary assay format for determining whether anantibody or antigen-binding fragment thereof binds to LEPR in complexwith human leptin is set forth in Example 4 herein.

Similarly, the present invention also includes antibodies andantigen-binding fragments thereof that bind LEPR and do not block theLEPR:leptin interaction. For example the present invention includesantibodies and antigen-binding fragments thereof that are capable ofbinding LEPR, thereby producing an antibody:LEPR complex, wherein theresulting antibody:LEPR complex is capable of interacting with leptin toproduce a three-member complex comprising the antibody, LEPR and leptin.An exemplary assay format for determining whether an antibody orantigen-binding fragment thereof is capable of binding LEPR in a mannerthat does not block or interfere with the interaction between LEPR andleptin is set forth in Example 5 herein.

The present invention also includes antibodies and antigen-bindingfragments thereof that bind cell surface-expressed LEPR in the presenceand/or absence of human leptin. Cell surface-expressed LEPR means LEPRor a portion thereof (e.g., an extracellular portion of LEPR) expressedon the surface of a cell, either naturally or in an engineered cellline, such that an antibody or antigen-binding fragment thereof iscapable of binding to the LEPR molecule. In certain embodiments, cellsurface-expressed LEPR includes recombinant complexes comprising anextracellular domain of LEPR connected to a cell via a tag or anchor(e.g., a GPI anchor as illustrated in Example 6 herein). According tothis aspect of the invention, antibodies are provided which are capableof binding cell surface-expressed LEPR in the absence of leptin, and arealso capable of binding cell surface-expressed LEPR in the presence ofleptin (i.e., under circumstances wherein leptin is capable of bindingto cell surface-expressed leptin). That is, according to certainembodiments, the interaction between anti-LEPR antibodies and cellsurface-expressed LEPR is not inhibited by the presence of leptin incomplex with cell surface-expressed LEPR. Antibodies according to thisaspect of the invention are capable of forming a three-member complex onthe surface of a cell comprising the antibody, cell surface-expressedLEPR and leptin. An exemplary assay format for determining whether anantibody or antigen-binding fragment thereof is capable of binding cellsurface-expressed LEPR in the presence and absence of human leptin isset forth in Example 6 herein.

The antibodies of the present invention may possess one or more of theaforementioned biological characteristics, or any combination thereof.The foregoing list of biological characteristics of the antibodies ofthe invention is not intended to be exhaustive. Other biologicalcharacteristics of the antibodies of the present invention will beevident to a person of ordinary skill in the art from a review of thepresent disclosure including the working Examples herein.

Epitope Mapping and Related Technologies

The present invention also includes anti-LEPR antibodies comprisingvariants of any of the HCVR, LCVR, and/or CDR amino acid sequencesdisclosed herein having one or more conservative substitutions. Forexample, the present invention includes anti-LEPR antibodies havingHCVR, LCVR, and/or CDR amino acid sequences with, e.g., 10 or fewer, 8or fewer, 6 or fewer, 4 or fewer, etc. conservative amino acidsubstitutions relative to any of the HCVR, LCVR, and/or CDR amino acidsequences set forth in Table 1 herein. In certain embodiments, thepresent invention provides anti-LEPR antibodies comprising variant HCVR,LCVR and/or CDR amino acid sequences relative to the sequences set forthin Table 1 herein (e.g., comprising conservative amino acidsubstitutions), wherein such variant antibodies nonetheless exhibit oneor more functions and/or properties of the exemplary anti-LEPRantibodies disclosed herein.

The extracellular domain of human LEPR contains an N-terminal cytokinereceptor homology domain (CRH-1), an immunoglobulin-like (Ig) domain,and a second CRH domain (CRH-2) that is referred to as theleptin-binding domain (LBD). (Carpenter et al. (2012) Structure20:487-97). Furthermore, LEPR shares the greatest homology and similarextracellular domain size and organization with granulocyte colonystimulating factor (GCSF) and glycoprotein 130 (gp13). (Haniu et al.(1998) J Biol Chem 273(44): 28691-699).

The term “epitope” refers to an antigenic determinant that interactswith a specific antigen binding site in the variable region of anantibody molecule known as a paratope. A single antigen may have morethan one epitope. Thus, different antibodies may bind to different areason an antigen and may have different biological effects. Epitopes may beeither conformational or linear. A conformational epitope is produced byspatially juxtaposed amino acids from different segments of the linearpolypeptide chain. A linear epitope is one produced by adjacent aminoacid residues in a polypeptide chain. In certain circumstance, anepitope may include moieties of saccharides, phosphoryl groups, orsulfonyl groups on the antigen.

The present invention includes anti-LEPR antibodies that interact withone or more epitopes found within amino acids M1-D839 of human LEPR (SEQID NO: 113). As set forth in Example 11, 201 peptides from human LEPRhad significantly reduced deuteration uptake when bound to antibodyH4H16650P2. The peptides corresponding to amino acids 162-169 (aminoacids LYVLPEVL of human LEPR, SEQ ID NO: 113) and 170-191 (amino acidsEDSPLVPQKGSF of human LEPR, SEQ ID NO: 113) had slower deuteration rateswhen bound to H4H16650P2, indicating that this antibody binds at leasttwo human LEPR epitopes having the sequences LYVLPEVL or EDSPLVPQKGSF(amino acids 162-169 or 170-191, respectively of SEQ ID NO: 113).

The epitope to which the antibodies of the present invention bind mayconsist of a single contiguous sequence of 3 or more (e.g., 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more) amino acidsof a LEPR protein. Alternatively, the epitope may consist of a pluralityof non-contiguous amino acids (or amino acid sequences) of LEPR. In someembodiments, the epitope is located on or near the leptin-binding domainof LEPR. In other embodiments, the epitope is located at a regiondistinct from the leptin-binding domain of LEPR, e.g., at a location onthe surface of LEPR at which an antibody, when bound to such an epitope,does not interfere with leptin binding to LEPR.

Various techniques known to persons of ordinary skill in the art can beused to identify the amino acids within an epitope recognized by aparticular antibody. Exemplary techniques include, e.g., alaninescanning mutational analysis, peptide blot analysis, and peptidecleavage analysis. In addition, methods such as epitope excision,epitope extraction and chemical modification of antigens can be employed(Tomer, 2000, Protein Science 9:487-496). Another method that can beused to identify the amino acids within a polypeptide with which anantibody interacts is hydrogen/deuterium exchange detected by massspectrometry. In general terms, the hydrogen/deuterium exchange methodinvolves deuterium-labeling the protein of interest, followed by bindingthe antibody to the deuterium-labeled protein. Next, theprotein/antibody complex is transferred to water to allowhydrogen-deuterium exchange to occur at all residues except for theresidues protected by the antibody (which remain deuterium-labeled).After dissociation of the antibody, the target protein is subjected toprotease cleavage and mass spectrometry analysis, thereby revealing thedeuterium-labeled residues which correspond to the specific amino acidswith which the antibody interacts. See, e.g., Ehring (1999) AnalyticalBiochemistry 267(2):252-259; Engen and Smith (2001) Anal. Chem.73:256A-265A. X-ray crystallography analysis of an antibody in complexwith its antigen may also be used to identify the amino acids within apolypeptide with which an antibody interacts.

The present invention further includes anti-LEPR antibodies that bind tothe same epitope as any of the specific exemplary antibodies describedherein (e.g. antibodies comprising any of the amino acid sequences asset forth in Table 1 herein). Likewise, the present invention alsoincludes anti-LEPR antibodies that compete for binding to LEPR with anyof the specific exemplary antibodies described herein (e.g. antibodiescomprising any of the amino acid sequences as set forth in Table 1herein).

One can determine whether an antibody binds to the same epitope as, orcompetes for binding with, a reference anti-LEPR antibody by usingroutine methods known in the art and exemplified herein. For example, todetermine if a test antibody binds to the same epitope as a referenceanti-LEPR antibody of the invention, the reference antibody is allowedto bind to a LEPR protein. Next, the ability of a test antibody to bindto the LEPR molecule is assessed. If the test antibody is able to bindto LEPR following saturation binding with the reference anti-LEPRantibody, it can be concluded that the test antibody binds to adifferent epitope than the reference anti-LEPR antibody. On the otherhand, if the test antibody is not able to bind to the LEPR moleculefollowing saturation binding with the reference anti-LEPR antibody, thenthe test antibody may bind to the same epitope as the epitope bound bythe reference anti-LEPR antibody of the invention. Additional routineexperimentation (e.g., peptide mutation and binding analyses) can thenbe carried out to confirm whether the observed lack of binding of thetest antibody is in fact due to binding to the same epitope as thereference antibody or if steric blocking (or another phenomenon) isresponsible for the lack of observed binding. Experiments of this sortcan be performed using ELISA, RIA, Biacore, flow cytometry or any otherquantitative or qualitative antibody-binding assay available in the art.In accordance with certain embodiments of the present invention, twoantibodies bind to the same (or overlapping) epitope if, e.g., a 1-, 5-,10-, 20- or 100-fold excess of one antibody inhibits binding of theother by at least 50% but preferably 75%, 90% or even 99% as measured ina competitive binding assay (see, e.g., Junghans et al., Cancer Res.1990:50:1495-1502). Alternatively, two antibodies are deemed to bind tothe same epitope if essentially all amino acid mutations in the antigenthat reduce or eliminate binding of one antibody reduce or eliminatebinding of the other. Two antibodies are deemed to have “overlappingepitopes” if only a subset of the amino acid mutations that reduce oreliminate binding of one antibody reduce or eliminate binding of theother.

To determine if an antibody competes for binding (or cross-competes forbinding) with a reference anti-LEPR antibody, the above-describedbinding methodology is performed in two orientations: In a firstorientation, the reference antibody is allowed to bind to a LEPR proteinunder saturating conditions followed by assessment of binding of thetest antibody to the LEPR molecule. In a second orientation, the testantibody is allowed to bind to a LEPR molecule under saturatingconditions followed by assessment of binding of the reference antibodyto the LEPR molecule. If, in both orientations, only the first(saturating) antibody is capable of binding to the LEPR molecule, thenit is concluded that the test antibody and the reference antibodycompete for binding to LEPR. As will be appreciated by a person ofordinary skill in the art, an antibody that competes for binding with areference antibody may not necessarily bind to the same epitope as thereference antibody, but may sterically block binding of the referenceantibody by binding an overlapping or adjacent epitope.

Preparation of Human Antibodies

The anti-LEPR antibodies of the present invention can be fully humanantibodies. Methods for generating monoclonal antibodies, includingfully human monoclonal antibodies are known in the art. Any such knownmethods can be used in the context of the present invention to makehuman antibodies that specifically bind to human LEPR.

Using VELOCIMMUNE™ technology, for example, or any other similar knownmethod for generating fully human monoclonal antibodies, high affinitychimeric antibodies to LEPR are initially isolated having a humanvariable region and a mouse constant region. As in the experimentalsection below, the antibodies are characterized and selected fordesirable characteristics, including affinity, ligand blocking activity,selectivity, epitope, etc. If necessary, mouse constant regions arereplaced with a desired human constant region, for example wild-type ormodified IgG1 or IgG4, to generate a fully human anti-LEPR antibody.While the constant region selected may vary according to specific use,high affinity antigen-binding and target specificity characteristicsreside in the variable region. In certain instances, fully humananti-LEPR antibodies are isolated directly from antigen-positive Bcells.

Bioequivalents

The anti-LEPR antibodies and antibody fragments of the present inventionencompass proteins having amino acid sequences that vary from those ofthe described antibodies but that retain the ability to bind human LEPR.Such variant antibodies and antibody fragments comprise one or moreadditions, deletions, or substitutions of amino acids when compared toparent sequence, but exhibit biological activity that is essentiallyequivalent to that of the described antibodies. Likewise, the anti-LEPRantibody-encoding DNA sequences of the present invention encompasssequences that comprise one or more additions, deletions, orsubstitutions of nucleotides when compared to the disclosed sequence,but that encode an anti-LEPR antibody or antibody fragment that isessentially bioequivalent to an anti-LEPR antibody or antibody fragmentof the invention. Examples of such variant amino acid and DNA sequencesare discussed above.

Two antigen-binding proteins, or antibodies, are consideredbioequivalent if, for example, they are pharmaceutical equivalents orpharmaceutical alternatives whose rate and extent of absorption do notshow a significant difference when administered at the same molar doseunder similar experimental conditions, either single does or multipledose. Some antibodies will be considered equivalents or pharmaceuticalalternatives if they are equivalent in the extent of their absorptionbut not in their rate of absorption and yet may be consideredbioequivalent because such differences in the rate of absorption areintentional and are reflected in the labeling, are not essential to theattainment of effective body drug concentrations on, e.g., chronic use,and are considered medically insignificant for the particular drugproduct studied.

In one embodiment, two antigen-binding proteins are bioequivalent ifthere are no clinically meaningful differences in their safety, purity,and potency.

In one embodiment, two antigen-binding proteins are bioequivalent if apatient can be switched one or more times between the reference productand the biological product without an expected increase in the risk ofadverse effects, including a clinically significant change inimmunogenicity, or diminished effectiveness, as compared to continuedtherapy without such switching.

In one embodiment, two antigen-binding proteins are bioequivalent ifthey both act by a common mechanism or mechanisms of action for thecondition or conditions of use, to the extent that such mechanisms areknown.

Bioequivalence may be demonstrated by in vivo and in vitro methods.Bioequivalence measures include, e.g., (a) an in vivo test in humans orother mammals, in which the concentration of the antibody or itsmetabolites is measured in blood, plasma, serum, or other biologicalfluid as a function of time; (b) an in vitro test that has beencorrelated with and is reasonably predictive of human in vivobioavailability data; (c) an in vivo test in humans or other mammals inwhich the appropriate acute pharmacological effect of the antibody (orits target) is measured as a function of time; and (d) in awell-controlled clinical trial that establishes safety, efficacy, orbioavailability or bioequivalence of an antibody.

Bioequivalent variants of anti-LEPR antibodies of the invention may beconstructed by, for example, making various substitutions of residues orsequences or deleting terminal or internal residues or sequences notneeded for biological activity. For example, cysteine residues notessential for biological activity can be deleted or replaced with otheramino acids to prevent formation of unnecessary or incorrectintramolecular disulfide bridges upon renaturation. In other contexts,bioequivalent antibodies may include anti-LEPR antibody variantscomprising amino acid changes which modify the glycosylationcharacteristics of the antibodies, e.g., mutations which eliminate orremove glycosylation.

Species Selectivity and Species Cross-Reactivity

The present invention, according to certain embodiments, providesanti-LEPR antibodies that bind to human LEPR but not to LEPR from otherspecies. The present invention also includes anti-LEPR antibodies thatbind to human LEPR and to LEPR from one or more non-human species. Forexample, the anti-LEPR antibodies of the invention may bind to humanLEPR and may bind or not bind, as the case may be, to one or more ofmouse, rat, guinea pig, hamster, gerbil, pig, cat, dog, rabbit, goat,sheep, cow, horse, camel, cynomologous, marmoset, rhesus or chimpanzeeLEPR. According to certain exemplary embodiments of the presentinvention, anti-LEPR antibodies are provided which specifically bindhuman LEPR and cynomolgus monkey (e.g., Macaca fascicularis) LEPR. Otheranti-LEPR antibodies of the invention bind human LEPR but do not bind,or bind only weakly, to cynomolgus monkey LEPR.

Multispecific Antibodies

The antibodies of the present invention may be monospecific ormultispecific (e.g., bispecific). Multispecific antibodies may bespecific for different epitopes of one target polypeptide or may containantigen-binding domains specific for more than one target polypeptide.See, e.g., Tutt et al., 1991, J. Immunol. 147:60-69; Kufer et al., 2004,Trends Biotechnol. 22:238-244. The anti-LEPR antibodies of the presentinvention can be linked to or co-expressed with another functionalmolecule, e.g., another peptide or protein. For example, an antibody orfragment thereof can be functionally linked (e.g., by chemical coupling,genetic fusion, noncovalent association or otherwise) to one or moreother molecular entities, such as another antibody or antibody fragmentto produce a bi-specific or a multispecific antibody with a secondbinding specificity.

The present invention includes bispecific antibodies wherein one arm ofan immunoglobulin binds human LEPR, and the other arm of theimmunoglobulin is specific for a second antigen. The LEPR-binding armcan comprise any of the HCVR/LCVR or CDR amino acid sequences as setforth in Table 1 herein.

An exemplary bispecific antibody format that can be used in the contextof the present invention involves the use of a first immunoglobulin (Ig)C_(H)3 domain and a second Ig C_(H)3 domain, wherein the first andsecond Ig C_(H)3 domains differ from one another by at least one aminoacid, and wherein at least one amino acid difference reduces binding ofthe bispecific antibody to Protein A as compared to a bi-specificantibody lacking the amino acid difference. In one embodiment, the firstIg C_(H)3 domain binds Protein A and the second Ig C_(H)3 domaincontains a mutation that reduces or abolishes Protein A binding such asan H95R modification (by IMGT exon numbering; H435R by EU numbering).The second C_(H)3 may further comprise a Y96F modification (by IMGT;Y436F by EU). Further modifications that may be found within the secondC_(H)3 include: D16E, L18M, N44S, K52N, V57M, and V821 (by IMGT; D356E,L358M, N384S, K392N, V397M, and V4221 by EU) in the case of IgG1antibodies; N44S, K52N, and V821 (IMGT; N384S, K392N, and V4221 by EU)in the case of IgG2 antibodies; and Q15R, N44S, K52N, V57M, R69K, E79Q,and V821 (by IMGT; Q355R, N384S, K392N, V397M, R409K, E419Q, and V4221by EU) in the case of IgG4 antibodies. Variations on the bispecificantibody format described above are contemplated within the scope of thepresent invention.

Other exemplary bispecific formats that can be used in the context ofthe present invention include, without limitation, e.g., scFv-based ordiabody bispecific formats, IgG-scFv fusions, dual variable domain(DVD)-Ig, Quadroma, knobs-into-holes, common light chain (e.g., commonlight chain with knobs-into-holes, etc.), CrossMab, CrossFab,(SEED)body, leucine zipper, Duobody, IgG1/IgG2, dual acting Fab(DAF)-IgG, and Mab² bispecific formats (see, e.g., Klein et al. 2012,mAbs 4:6, 1-11, and references cited therein, for a review of theforegoing formats). Bispecific antibodies can also be constructed usingpeptide/nucleic acid conjugation, e.g., wherein unnatural amino acidswith orthogonal chemical reactivity are used to generate site-specificantibody-oligonucleotide conjugates which then self-assemble intomultimeric complexes with defined composition, valency and geometry.(See, e.g., Kazane et al., J. Am. Chem. Soc. [Epub: Dec. 4, 2012]).

Therapeutic Formulation and Administration

The invention provides pharmaceutical compositions comprising theanti-LEPR antibodies or antigen-binding fragments thereof of the presentinvention. The pharmaceutical compositions of the invention areformulated with suitable carriers, excipients, and other agents thatprovide improved transfer, delivery, tolerance, and the like. Amultitude of appropriate formulations can be found in the formularyknown to all pharmaceutical chemists: Remington's PharmaceuticalSciences, Mack Publishing Company, Easton, Pa. These formulationsinclude, for example, powders, pastes, ointments, jellies, waxes, oils,lipids, lipid (cationic or anionic) containing vesicles (such asLIPOFECTIN™, Life Technologies, Carlsbad, Calif.), DNA conjugates,anhydrous absorption pastes, oil-in-water and water-in-oil emulsions,emulsions carbowax (polyethylene glycols of various molecular weights),semi-solid gels, and semi-solid mixtures containing carbowax. See alsoPowell et al. “Compendium of excipients for parenteral formulations” PDA(1998) J Pharm Sci Technol 52:238-311.

The dose of antibody administered to a patient may vary depending uponthe age and the size of the patient, target disease, conditions, routeof administration, and the like. The preferred dose is typicallycalculated according to body weight or body surface area. In an adultpatient, it may be advantageous to intravenously administer the antibodyof the present invention normally at a single dose of about 0.01 toabout 20 mg/kg body weight, more preferably about 0.02 to about 7, about0.03 to about 5, or about 0.05 to about 3 mg/kg body weight. Dependingon the severity of the condition, the frequency and the duration of thetreatment can be adjusted. Effective dosages and schedules foradministering anti-LEPR antibodies may be determined empirically; forexample, patient progress can be monitored by periodic assessment, andthe dose adjusted accordingly. Moreover, interspecies scaling of dosagescan be performed using well-known methods in the art (e.g., Mordenti etaL, 1991, Pharmaceut. Res. 8:1351).

Various delivery systems are known and can be used to administer thepharmaceutical composition of the invention, e.g., encapsulation inliposomes, microparticles, microcapsules, recombinant cells capable ofexpressing the mutant viruses, receptor mediated endocytosis (see, e.g.,Wu et al., 1987, J. Biol. Chem. 262:4429-4432). Methods of introductioninclude, but are not limited to, intradermal, intramuscular,intraperitoneal, intravenous, subcutaneous, intranasal, epidural, andoral routes. The composition may be administered by any convenientroute, for example by infusion or bolus injection, by absorption throughepithelial or mucocutaneous linings (e.g., oral mucosa, rectal andintestinal mucosa, etc.) and may be administered together with otherbiologically active agents. Administration can be systemic or local.

A pharmaceutical composition of the present invention can be deliveredsubcutaneously or intravenously with a standard needle and syringe. Inaddition, with respect to subcutaneous delivery, a pen delivery devicereadily has applications in delivering a pharmaceutical composition ofthe present invention. Such a pen delivery device can be reusable ordisposable. A reusable pen delivery device generally utilizes areplaceable cartridge that contains a pharmaceutical composition. Onceall of the pharmaceutical composition within the cartridge has beenadministered and the cartridge is empty, the empty cartridge can readilybe discarded and replaced with a new cartridge that contains thepharmaceutical composition. The pen delivery device can then be reused.In a disposable pen delivery device, there is no replaceable cartridge.Rather, the disposable pen delivery device comes prefilled with thepharmaceutical composition held in a reservoir within the device. Oncethe reservoir is emptied of the pharmaceutical composition, the entiredevice is discarded.

Numerous reusable pen and autoinjector delivery devices haveapplications in the subcutaneous delivery of a pharmaceuticalcomposition of the present invention. Examples include, but are notlimited to AUTOPENTM (Owen Mumford, Inc., Woodstock, UK), DISETRONIC™pen (Disetronic Medical Systems, Bergdorf, Switzerland), HUMALOG MIX75/25™ pen, HUMALOG™ pen, HUMALIN 70/30™ pen (Eli Lilly and Co.,Indianapolis, Ind.), NOVOPEN™ I, II and III (Novo Nordisk, Copenhagen,Denmark), NOVOPEN JUNIOR™ (Novo Nordisk, Copenhagen, Denmark), BD™ pen(Becton Dickinson, Franklin Lakes, N.J.), OPTIPEN™, OPTIPEN PRO™,OPTIPEN STARLET™, and OPTICLIK™ (Sanofi-Aventis, Frankfurt, Germany), toname only a few. Examples of disposable pen delivery devices havingapplications in subcutaneous delivery of a pharmaceutical composition ofthe present invention include, but are not limited to the SOLOSTAR™ pen(Sanofi-Aventis), the FLEXPEN™ (Novo Nordisk), and the KWIKPEN™ (EliLilly), the SURECLICK™ Autoinjector (Amgen, Thousand Oaks, Calif.), thePENLET™ (Haselmeier, Stuttgart, Germany), the EPIPEN (Dey, L.P.), andthe HUMIRA™ Pen (Abbott Labs, Abbott Park Ill.), to name only a few.

In certain situations, the pharmaceutical composition can be deliveredin a controlled release system. In one embodiment, a pump may be used(see Langer, supra; Sefton, 1987, CRC Crit. Ref. Biomed. Eng. 14:201).In another embodiment, polymeric materials can be used; see, MedicalApplications of Controlled Release, Langer and Wise (eds.), 1974, CRCPres., Boca Raton, Fla. In yet another embodiment, a controlled releasesystem can be placed in proximity of the composition's target, thusrequiring only a fraction of the systemic dose (see, e.g., Goodson,1984, in Medical Applications of Controlled Release, supra, vol. 2, pp.115-138). Other controlled release systems are discussed in the reviewby Langer, 1990, Science 249:1527-1533.

The injectable preparations may include dosage forms for intravenous,subcutaneous, intracutaneous and intramuscular injections, dripinfusions, etc. These injectable preparations may be prepared by methodspublicly known. For example, the injectable preparations may beprepared, e.g., by dissolving, suspending or emulsifying the antibody orits salt described above in a sterile aqueous medium or an oily mediumconventionally used for injections. As the aqueous medium forinjections, there are, for example, physiological saline, an isotonicsolution containing glucose and other auxiliary agents, etc., which maybe used in combination with an appropriate solubilizing agent such as analcohol (e.g., ethanol), a polyalcohol (e.g., propylene glycol,polyethylene glycol), a nonionic surfactant [e.g., polysorbate 80,HCO-50 (polyoxyethylene (50 mol) adduct of hydrogenated castor oil)],etc. As the oily medium, there are employed, e.g., sesame oil, soybeanoil, etc., which may be used in combination with a solubilizing agentsuch as benzyl benzoate, benzyl alcohol, etc. The injection thusprepared is preferably filled in an appropriate ampoule.

Advantageously, the pharmaceutical compositions for oral or parenteraluse described above are prepared into dosage forms in a unit dose suitedto fit a dose of the active ingredients. Such dosage forms in a unitdose include, for example, tablets, pills, capsules, injections(ampoules), suppositories, etc. The amount of the aforesaid antibodycontained is generally about 5 to about 500 mg per dosage form in a unitdose; especially in the form of injection, it is preferred that theaforesaid antibody is contained in about 5 to about 100 mg and in about10 to about 250 mg for the other dosage forms.

Therapeutic Uses of the Antibodies

The present invention includes methods comprising administering to asubject in need thereof a therapeutic composition comprising ananti-LEPR antibody (e.g., an anti-LEPR antibody comprising any of theHCVR/LCVR or CDR sequences as set forth in Table 1 herein). Thetherapeutic composition can comprise any of the anti-LEPR antibodiesdisclosed herein, or antigen-binding fragments thereof, and apharmaceutically acceptable carrier or diluent.

The antibodies of the invention are useful, inter alia, for thetreatment, prevention and/or amelioration of any disease or disorderassociated with or mediated by leptin deficiency, leptin resistance,hypoleptinemia, or otherwise treatable by stimulating or activating LEPRsignaling or mimicking the natural activity of leptin in vitro or invivo. For example, the antibodies and antigen-binding fragments thereofof the present invention are useful for treating lipodystrophyconditions. Exemplary lipodystrophy conditions that are treatable by theantibodies and antigen-binding fragments of the present inventioninclude, e.g., congenital generalized lipodystrophy, acquiredgeneralized lipodystrophy, familial partial lipodystrophy, acquiredpartial lipodystrophy, centrifugal abdominal lipodystrophy, lipoatrophiaannularis, localized lipodystrophy, and HIV-associated lipodystrophy.

The present invention also includes anti-LEPR antibodies andantigen-binding fragments thereof that are useful for restoring leptinsignaling to cells, tissues and organs expressing one or more LEPRmutations associated with obesity. For example, certain LEPR mutantshave been identified that exhibit no, or reduced signaling in thepresence of leptin and are associated with obesity and relateddisorders. As used herein, a LEPR mutant that exhibits no signaling inthe presence of leptin is referred to as a “signaling-defective LEPRmutant.” An exemplary signaling-defective LEPR mutation is LEPR-A409E(Farooqi et al., 2007, N Engl J Med 356(3): 237-247). As used herein, aLEPR mutant that exhibits reduced signaling in the presence of leptin(as compared to wild-type LEPR) is referred to as a “signaling-impairedLEPR mutant.” An exemplary signaling-impaired LEPR mutation isLEPR-P316T (Mazen et al., 2011, Mol Genet Metab 102:461-464). Thus, thepresent invention includes anti-LEPR antibodies and antigen-bindingfragments thereof that are useful for the treatment, prevention and/oramelioration of diseases and disorders caused by or associated with oneor more signaling-defective (e.g., A409E) and/or signaling-impaired(e.g., P316T) LEPR mutants.

The anti-LEPR antibodies and antigen-binding fragments thereof of thepresent invention are also useful for the treatment or prevention of oneor more diseases or disorders selected from the group consisting ofobesity, metabolic syndrome, diet-induced food craving, functionalhypothalamic amenorrhea, type 1 diabetes, type 2 diabetes, insulinresistance, severe insulin resistance including severe insulinresistance due to mutation in insulin receptor, severe insulinresistance not caused by mutation in the insulin receptor, severeinsulin resistance caused by a mutation in downstream signaling pathwaysor induced by other causes, non-alcoholic and alcoholic fatty liverdiseases, Alzheimer's disease, leptin deficiency, leptin resistance,lipodystrophies, Leprechaunism/Donohue syndrome, Rabson-Mendenhallsyndrome.

In the context of the methods of treatment described herein, theanti-LEPR antibody may be administered as a monotherapy (i.e., as theonly therapeutic agent) or in combination with one or more additionaltherapeutic agents (examples of which are described elsewhere herein).

Combination Therapies and Formulations

The present invention includes compositions and therapeutic formulationscomprising any of the anti-LEPR antibodies described herein incombination with one or more additional therapeutically activecomponents, and methods of treatment comprising administering suchcombinations to subjects in need thereof.

The anti-LEPR antibodies of the present invention may be co-formulatedwith and/or administered in combination with one or more additionaltherapeutically active component(s), such as. e.g., pharmaceuticalproducts prescribed for the treatment of obesity, hypercholesterolemia,hyperlipidemia, type 2 diabetes, type 1 diabetes, appetite control,infertility, etc. Examples of such additional therapeutically activecomponents include, e.g., recombinant human leptin (e.g., metreleptin[MYALEPT]), PCSK9 inhibitors (e.g., anti-PCSK9 antibodies [alirocumab,evolocumab, bococizumab, lodelcizumab, ralpancizumab, etc.]), statins(atorvastatin, rosuvastatin, cerivastatin, pitavastatin, fluvastatin,simvastatin, lovastatin, pravastatin, etc.), ezetimibe, insulin, insulinvariants, insulin secretagogues, metformin, sulfonylureas, sodiumglucose cotransporter 2 (SGLT2) Inhibitors (e.g., dapaglifozin,canaglifozin, empagliflozin, etc.), GLP-1 agonists/analogues (e.g.,extendin-4, exenatide, liraglutide, lixisenatide, albiglutide,dulaglutide, etc.), glucagon (GCG) inhibitors (e.g., anti-GCGantibodies), glucagon receptor (GCGR) inhibitors (e.g., anti-GCGRantibodies, small molecule GCGR antagonists, GCGR-specific antisenseoligonucleotides, anti-GCGR aptamers [e.g., Spiegelmers], etc.),angiopoietin-like protein (ANGPTL) inhibitors (e.g., anti-ANGPTL3antibodies, anti-ANGPTL4 antibodies, anti-ANGPTL8 antibodies, etc.),Phentermine, Orlistat, Topiramate, Bupropion, Topiramate/Phentermine,Bupropion/Naltrexone, Bupropion/Zonisamide, Pramlintide/Metrelepin,Lorcaserin, Cetilistat, Tesofensine, Velneperit, etc.

The additional therapeutically active component(s), e.g., any of theagents listed above or derivatives thereof, may be administered justprior to, concurrent with, or shortly after the administration of ananti-LEPR antibody of the present invention; (for purposes of thepresent disclosure, such administration regimens are considered theadministration of an anti-LEPR antibody “in combination with” anadditional therapeutically active component). The present inventionincludes pharmaceutical compositions in which an anti-LEPR antibody ofthe present invention is co-formulated with one or more of theadditional therapeutically active component(s) as described elsewhereherein.

Administration Regimens

According to certain embodiments of the present invention, multipledoses of an anti-LEPR antibody (or a pharmaceutical compositioncomprising a combination of an anti-LEPR antibody and any of theadditional therapeutically active agents mentioned herein) may beadministered to a subject over a defined time course. The methodsaccording to this aspect of the invention comprise sequentiallyadministering to a subject multiple doses of an anti-LEPR antibody ofthe invention. As used herein, “sequentially administering” means thateach dose of anti-LEPR antibody is administered to the subject at adifferent point in time, e.g., on different days separated by apredetermined interval (e.g., hours, days, weeks or months). The presentinvention includes methods which comprise sequentially administering tothe patient a single initial dose of an anti-LEPR antibody, followed byone or more secondary doses of the anti-LEPR antibody, and optionallyfollowed by one or more tertiary doses of the anti-LEPR antibody.

The terms “initial dose,” “secondary doses,” and “tertiary doses,” referto the temporal sequence of administration of the anti-LEPR antibody ofthe invention. Thus, the “initial dose” is the dose which isadministered at the beginning of the treatment regimen (also referred toas the “baseline dose,” “loading dose,” “starting dose,” and the like);the “secondary doses” are the doses which are administered after theinitial dose; and the “tertiary doses” are the doses which areadministered after the secondary doses. The initial, secondary, andtertiary doses may all contain the same amount of anti-LEPR antibody,but generally may differ from one another in terms of frequency ofadministration. In certain embodiments, however, the amount of anti-LEPRantibody contained in the initial, secondary and/or tertiary dosesvaries from one another (e.g., adjusted up or down as appropriate)during the course of treatment. In certain embodiments, two or more(e.g., 2, 3, 4, or 5) doses are administered at the beginning of thetreatment regimen as “loading doses” followed by subsequent doses thatare administered on a less frequent basis (e.g., “maintenance doses”).

Diagnostic and Analytic Uses of the Antibodies

The anti-LEPR antibodies of the present invention may also be used todetect and/or measure LEPR, or LEPR-expressing cells in a sample, e.g.,for diagnostic purposes. For example, an anti-LEPR antibody, or fragmentthereof, may be used to diagnose a condition or disease characterized byaberrant expression (e.g., over-expression, under-expression, lack ofexpression, etc.) of LEPR. Exemplary diagnostic assays for LEPR maycomprise, e.g., contacting a sample, obtained from a patient, with ananti-LEPR antibody of the invention, wherein the anti-LEPR antibody islabeled with a detectable label or reporter molecule. Alternatively, anunlabeled anti-LEPR antibody can be used in diagnostic applications incombination with a secondary antibody which is itself detectablylabeled. The detectable label or reporter molecule can be aradioisotope, such as ³H, ¹⁴C, ³²P, ³⁵S, or ¹²⁵I; a fluorescent orchemiluminescent moiety such as fluorescein isothiocyanate, orrhodamine; or an enzyme such as alkaline phosphatase,beta-galactosidase, horseradish peroxidase, or luciferase. Specificexemplary assays that can be used to detect or measure LEPR in a sampleinclude enzyme-linked immunosorbent assay (ELISA), radioimmunoassay(RIA), fluorescence-activated cell sorting (FACS), and positron emissiontomography (PET) scanning.

Samples that can be used in LEPR diagnostic assays according to thepresent invention include any tissue or fluid sample obtainable from apatient which contains detectable quantities of LEPR protein, orfragments thereof, under normal or pathological conditions. Generally,levels of LEPR in a particular sample obtained from a healthy patient(e.g., a patient not afflicted with a disease or condition associatedwith abnormal LEPR levels or activity) will be measured to initiallyestablish a baseline, or standard, level of LEPR. This baseline level ofLEPR can then be compared against the levels of LEPR measured in samplesobtained from individuals suspected of having a LEPR related disease orcondition.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how tomake and use the methods and compositions of the invention, and are notintended to limit the scope of what the inventors regard as theirinvention. Efforts have been made to ensure accuracy with respect tonumbers used (e.g., amounts, temperature, etc.) but some experimentalerrors and deviations should be accounted for. Unless indicatedotherwise, parts are parts by weight, molecular weight is averagemolecular weight, temperature is in degrees Centigrade, and pressure isat or near atmospheric.

Example 1 Generation of Antigen-Binding Proteins that Specifically Bindthe Leptin Receptor (LEPR)

Anti-LEPR antibodies were obtained by immunizing a VELOCIMMUNE® mouse(i.e., an engineered mouse comprising DNA encoding human immunoglobulinheavy and kappa light chain variable regions) with an immunogencomprising the extracellular domain of LEPR. The antibody immuneresponse was monitored by a LEPR-specific immunoassay. Using previouslydescribed techniques, fully human anti-LEPR antibodies were isolated andpurified.

Certain biological properties of the exemplary anti-LEPR antibodiesgenerated in accordance with the methods of this Example are describedin detail in the Examples set forth below.

Example 2 Heavy and Light Chain Variable Region Amino Acid and NucleicAcid Sequences

Table 1 sets forth the amino acid sequence identifiers of the heavy andlight chain variable regions and CDRs of selected anti-LEPR antibodiesof the invention. The corresponding nucleic acid sequence identifiersare set forth in Table 2.

TABLE 1 Amino Acid Sequence Identifiers Antibody SEQ ID NOs: DesignationHCVR HCDR1 HCDR2 HCDR3 LCVR LCDR1 LCDR2 LCDR3 H4H16650P2 2 4 6 8 10 1214 16 H4H16679P2 18 20 22 24 10 12 14 16 H4H17319P2 26 28 30 32 10 12 1416 H4H17321P2 34 36 38 40 10 12 14 16 H4H18417P2 42 44 46 48 10 12 14 16H4H18438P2 50 52 54 56 10 12 14 16 H4H18445P2 58 60 62 64 10 12 14 16H4H18446P2 66 68 70 72 10 12 14 16 H4H18449P2 74 76 78 80 10 12 14 16H4H18482P2 82 84 86 88 90 92 94 96 H4H18487P2 98 100 102 104 90 92 94 96H4H18492P2 106 108 110 112 90 92 94 96

TABLE 2 Nucleic Acid Sequence Identifiers Antibody SEQ ID NOs:Designation HCVR HCDR1 HCDR2 HCDR3 LCVR LCDR1 LCDR2 LCDR3 H4H16650P2 1 35 7 9 11 13 15 H4H16679P2 17 19 21 23 9 11 13 15 H4H17319P2 25 27 29 319 11 13 15 H4H17321P2 33 35 37 39 9 11 13 15 H4H18417P2 41 43 45 47 9 1113 15 H4H18438P2 49 51 53 55 9 11 13 15 H4H18445P2 57 59 61 63 9 11 1315 H4H18446P2 65 67 69 71 9 11 13 15 H4H18449P2 73 75 77 79 9 11 13 15H4H18482P2 81 83 85 87 89 91 93 95 H4H18487P2 97 99 101 103 89 91 93 95H4H18492P2 105 107 109 111 89 91 93 95

Antibodies are typically referred to herein according to the followingnomenclature: Fc prefix (e.g. “H4H,” “H1M,” “H2M,” etc.), followed by anumerical identifier (e.g. “16650,” “16679,” etc.), followed by a “P” or“N” suffix. Thus, according to this nomenclature, an antibody may bereferred to herein as, e.g., “H4H16650P2,” “H4H16679P2,” etc. The Fcprefixes on the antibody designations used herein (H4H, H1M and H2M)indicate the particular Fc region isotype of the antibody. For example,an “H4H” antibody has a human IgG4 Fc, whereas an “H1M” antibody has amouse IgG1 Fc, (all variable regions are fully human as denoted by thefirst ‘H’ in the antibody designation). As will be appreciated by aperson of ordinary skill in the art, an antibody having a particular Fcisotype can be converted to an antibody with a different Fc isotype(e.g., an antibody with a mouse IgG1 Fc can be converted to an antibodywith a human IgG4, etc.), but in any event, the variable domains(including the CDRs)—which are indicated by the numerical identifiersshown in Tables 1 and 2—will remain the same, and the binding propertiesare expected to be identical or substantially similar regardless of thenature of the Fc domain.

“Comparator mAb” as used in Examples herein refers to Fab9F8 describedin Fazeli et al. (2006) J Immunol Methods 312:190-200 and Carpenter etal. (2012) Structure 20(3):487-97.

Example 3 Surface Plasmon Resonance Derived Binding Affinities andKinetic Constants of Human Monoclonal Anti-LEPR Antibodies

Equilibrium dissociation constants (K_(D) values) for LEPR binding topurified anti-LEPR monoclonal antibodies were determined using areal-time surface plasmon resonance biosensor using a Biacore 4000instrument. All binding studies were performed in 10 mM HEPES, 150 mMNaCl, 3 mM EDTA, and 0.05% v/v Surfactant Tween-20, pH 7.4 (HBS-ET)running buffer at 25° C. and 37° C. The Biacore sensor surface was firstderivatized by amine coupling with a monoclonal mouse anti-human Fcantibody (GE, #BR-1008-39) to capture anti-LEPR monoclonal antibodies.Binding studies were performed on following LEPR reagents: human LEPRextracellular domain expressed with a C-terminal myc-myc-hexahistidinetag (hLEPR.mmh; SEQ ID NO: 114), macaca fascicularis LEPR extracellulardomain expressed with a C-terminal myc-myc-hexahistidine tag(mfLEPR.mmh; SEQ ID NO: 117), human LEPR extracellular domain expressedwith a C-terminal mouse IgG2a Fc tag (hLEPR.mFc; SEQ ID NO: 115), mouseLEPR extracellular domain expressed with a C-terminalmyc-myc-hexahistidine tag (mLEPR.mmh; SEQ ID NO: 118) and rat LEPRextracellular domain expressed with a C-terminal myc-myc-hexahistidinetag (rLEPR.mmh; SEQ ID NO: 119). Different concentrations of LEPRreagents were first prepared in HBS-ET running buffer (100 nM-3.7 nM;3-fold serial dilution) and were injected over anti-human Fc capturedanti-LEPR monoclonal antibody surface for 4 minutes at a flow rate of 30μL/minute, while the dissociation of monoclonal antibody bound LEPRreagent was monitored for 10 minutes in HBS-ET running buffer. Kineticassociation (k_(a)) and dissociation (k_(d)) rate constants weredetermined by fitting the real-time binding sensorgrams to a 1:1 bindingmodel with mass transport limitation using Scrubber 2.0c curve-fittingsoftware. Binding dissociation equilibrium constants (K_(D)) anddissociative half-lives (t½) were calculated from the kinetic rateconstants as:

${{K_{D}(M)} = \frac{kd}{ka}},{{{and}\mspace{14mu} t\frac{1}{2}\left( \min \right)} = \frac{\ln (2)}{60*{kd}}}$

Binding kinetics parameters for hLEPR.mmh, mfLEPR.MMH or hLEPR.mFc,binding to different anti-LEPR monoclonal antibodies of the invention at25° C. and 37° C. are shown in Tables 3 through 8.

TABLE 3 Binding kinetics parameters of hLEPR-MMH binding to LEPRmonoclonal antibodies at 25° C. 100 nM hLEPR- mAb MMH Capture Boundk_(a) k_(d) K_(D) t½ mAb Captured Level (RU) (RU) (1/Ms) (1/s) (M) (min)H4H16650P2 167 ± 0.3 51 2.81E+04 2.23E−04 7.93E−09 52 H4H16679P2 192 ±0.7 39 2.34E+04 2.46E−04 1.05E−08 47 H4H18417P2 163 ± 0.4 28 6.14E+047.90E−03 1.29E−07 1.5 H4H18438P2 166 ± 0.4 22 3.00E+04 2.26E−03 7.54E−085.1 H4H18445P2 194 ± 1.1 45 4.42E+04 4.78E−03 1.08E−07 2.4 H4H18446P2163 ± 2.4 16 1.81E+04 9.51E−04 5.25E−08 12 H4H18449P2 176 ± 1.3 542.91E+04 2.35E−04 8.08E−09 49 H4H18482P2 163 ± 0.4 47 6.31E+04 6.77E−031.07E−07 1.7 H4H18487P2 190 ± 1.2 42 4.73E+04 7.03E−03 1.48E−07 1.6H4H18492P2 167 ± 3.1 87 8.10E+04 8.98E−04 1.11E−08 13 H4H17319P2 200 ±0.4 36 2.61E+04 5.29E−04 2.03E−08 22 H4H17321P2 221 ± 0.5 32 2.36E+041.96E−04 8.31E−09 59 Isotype Control 171 ± 0.4 4 NB* NB* NB* NB* mAb *NBindicates that no binding was observed under the current experimentalconditions.

TABLE 4 Binding kinetics parameters of hLEPR-MMH binding to LEPRmonoclonal antibodies at 37° C. 100 nM hLEPR- mAb MMH Capture Boundk_(a) k_(d) K_(D) t½ mAb Captured Level (RU) (RU) (1/Ms) (1/s) (M) (min)H4H16650P2 210 ± 2.5 77 4.85E+04 9.58E−04 1.98E−08 12 H4H16679P2 239 ±2   61 3.84E+04 8.42E−04 2.19E−08 14 H4H18417P2 206 ± 3.2 22 7.70E+041.80E−02 2.33E−07 0.6 H4H18438P2 206 ± 2.4 32 3.38E+04 5.76E−03 1.70E−072.0 H4H18445P2 234 ± 2   38 5.13E+04 1.68E−02 3.26E−07 0.7 H4H18446P2188 ± 3.4 21 2.12E+04 2.56E−03 1.21E−07 4.5 H4H18449P2 206 ± 2.1 733.94E+04 8.15E−04 2.07E−08 14 H4H18482P2 188 ± 0.8 38 9.53E+04 1.93E−022.03E−07 0.6 H4H18487P2 219 ± 1.7 30 6.51E+04 1.86E−02 2.86E−07 0.6H4H18492P2 192 ± 2.2 93 1.17E+05 4.18E−03 3.59E−08 2.8 H4H17319P2 264 ±0.3 44 3.54E+04 3.41E−03 9.63E−08 3.4 H4H17321P2 290 ± 0.4 61 2.95E+044.38E−04 1.48E−08 26 Isotype Control 193 ± 1.5 6 NB* NB* NB* NB* mAb *NBindicates that no binding was observed under the current experimentalconditions.

TABLE 5 Binding kinetics parameters of mfLEPR.MMH binding to LEPRmonoclonal antibodies at 25° C. 100 nM mfLEP. mAb MMH Capture Boundk_(a) k_(d) K_(D) t½ mAb Captured Level (RU) (RU) (1/Ms) (1/s) (M) (min)H4H16650P2 166 ± 0.6 93 6.02E+04 1.37E−04 2.27E−09 84 H4H16679P2 191 ±0.7 66 4.37E+04 1.41E−04 3.22E−09 82 H4H18417P2 162 ± 0.3 33 8.83E+041.23E−02 1.39E−07 0.9 H4H18438P2 166 ± 0.6 5 IC* IC* IC* IC* H4H18445P2193 ± 0.6 58 5.90E+04 4.86E−03 8.24E−08 2.4 H4H18446P2 163 ± 2.8 231.93E+04 1.12E−03 5.83E−08 10 H4H18449P2 175 ± 0.5 6 IC* IC* IC* IC*H4H18482P2 163 ± 0.8 63 1.01E+05 6.74E−03 6.66E−08 1.7 H4H18487P2 189 ±0.5 59 7.37E+04 6.79E−03 9.21E−08 1.7 H4H18492P2 165 ± 2.4 52 1.10E+051.20E−02 1.10E−07 1.0 H4H17319P2 213 ± 0.5 83 4.00E+04 4.63E−04 1.16E−0825 H4H17321P2 236 ± 0.4 75 3.26E+04 1.33E−04 4.07E−09 87 Isotype Control171 ± 0.4 0 NB* NB* NB* NB* mAb *NB indicates that no binding wasobserved under the current experimental conditions. *IC indicates thatobserved binding was inclusive and was unable to fit the real timebinding data under the current experimental conditions.

TABLE 6 Binding kinetics parameters of mfLEPR.MMH binding to LEPRmonoclonal antibodies at 37° C. 100 nM mfLEPR. mAb MMH Capture Boundk_(a) k_(d) K_(D) t½ mAb Captured Level (RU) (RU) (1/Ms) (1/s) (M) (min)H4H16650P2 204 ± 1.7 134 1.22E+05 7.00E−04 5.76E−09 16 H4H16679P2 232 ±1.1 104 6.49E+04 6.77E−04 1.04E−08 17 H4H18417P2 202 ± 1.3 28 1.22E+052.63E−02 2.17E−07 0.4 H4H18438P2 203 ± 1.3 7 IC* IC* IC* IC* H4H18445P2232 ± 0.9 48 7.17E+04 1.90E−02 2.64E−07 0.6 H4H18446P2 188 ± 2.9 302.53E+04 3.54E−03 1.40E−07 3.3 H4H18449P2 202 ± 1   6 IC* IC* IC* IC*H4H18482P2 187 ± 1.2 52 1.52E+05 2.04E−02 1.34E−07 0.6 H4H18487P2 216 ±0.7 44 1.10E+05 1.95E−02 1.78E−07 0.6 H4H18492P2 191 ± 1.4 34 2.34E+053.94E−02 1.69E−07 0.3 H4H17319P2 274 ± 0.5 113 5.39E+04 3.24E−036.01E−08 3.6 H4H17321P2 304 ± 0.7 143 4.97E+04 2.57E−04 5.18E−09 45Isotype Control 190 ± 1   1 NB* NB* NB* NB* mAb *NB indicates that nobinding was observed under the current experimental conditions. *ICindicates that observed binding was inclusive and was unable to fit thereal time binding data under the current experimental conditions.

TABLE 7 Binding kinetics parameters of hLEPR.mFc binding to LEPRmonoclonal antibodies at 25° C. 100 nM hLEPR- mAb mFc Capture Boundk_(a) k_(d) K_(D) t½ mAb Captured Level (RU) (RU) (1/Ms) (1/s) (M) (min)H4H16650P2 165 ± 0.2 102 1.06E+05 8.32E−05 7.85E−10 139 H4H16679P2 190 ±1.2 78 5.84E+04 9.68E−05 1.66E−09 119 H4H18417P2 162 ± 0.6 90 1.40E+055.63E−04 4.04E−09 21 H4H18438P2 165 ± 1.2 51 5.19E+04 2.44E−04 4.70E−0947 H4H18445P2 192 ± 0.4 76 1.22E+05 4.92E−04 4.03E−09 23 H4H18446P2 162± 2.8 20 3.20E+04 2.08E−04 6.48E−09 56 H4H18449P2 174 ± 0.6 116 7.05E+046.82E−05 9.64E−10 169 H4H18482P2 162 ± 0.5 88 1.44E+05 4.91E−04 3.42E−0924 H4H18487P2 188 ± 0.6 85 1.06E+05 6.03E−04 5.70E−09 19 H4H18492P2 166± 3.2 129 2.27E+05 1.39E−04 6.13E−10 83 H4H17319P2 200 ± 0.5 69 4.77E+041.64E−04 3.45E−09 70 H4H17321P2 221 ± 0.4 65 4.10E+04 8.93E−05 2.18E−09129 Isotype Control 170 ± 0.7 −2 NB* NB* NB* NB* mAb *NB indicates thatno binding was observed under the current experimental conditions.

TABLE 8 Binding kinetics parameters of hLEPR.mFc binding to LEPRmonoclonal antibodies at 37° C. 100 nM hLEPR- mAb mFc Capture Boundk_(a) k_(d) K_(D) t½ mAb Captured Level (RU) (RU) (1/Ms) (1/s) (M) (min)H4H16650P2 199 ± 1.9 145 1.57E+05 2.80E−04 1.79E−09 41 H4H16679P2 229 ±2.3 116 1.21E+05 3.10E−04 2.56E−09 37 H4H18417P2 199 ± 1.1 111 1.85E+051.05E−03 5.64E−09 11 H4H18438P2 199 ± 0.6 82 7.02E+04 5.98E−04 8.53E−0919 H4H18445P2 229 ± 2   104 1.56E+05 6.08E−04 3.89E−09 19 H4H18446P2 186± 2.5 34 4.27E+04 5.48E−04 1.28E−08 21 H4H18449P2 198 ± 1.6 148 1.33E+051.68E−04 1.26E−09 69 H4H18482P2 185 ± 1.3 109 1.89E+05 7.26E−04 3.84E−0916 H4H18487P2 215 ± 1.5 99 1.23E+05 6.06E−04 4.93E−09 19 H4H18492P2 189± 1.8 160 4.33E+05 5.00E−04 1.16E−09 23 H4H17319P2 262 ± 0.5 1008.51E+04 6.52E−04 7.66E−09 18 H4H17321P2 289 ± 0.4 110 5.53E+04 1.74E−043.15E−09 66 Isotype Control 188 ± 0.8 1 NB* NB* NB* NB* mAb *NBindicates that no binding was observed under the current experimentalconditions.

At 25° C., anti-LEPR monoclonal antibodies bound to hLEPR-MMH with K_(D)values ranging from 7.93 nM to 148 nM, as shown in Table 5. At 37° C.,anti-LEPR monoclonal antibodies bound to hLEPR-MMH with K_(D) valuesranging from 14.8 nM to 326 nM, as shown in Table 4.

Ten out of 12 anti-LEPR monoclonal antibodies of the invention bound tomfLEPR.MMH. At 25° C., anti-LEPR monoclonal antibodies bound tomfLEPR.MMH with K_(D) values ranging from 2.27 nM to 139 nM, as shown inTable 7. At 37° C., anti-LEPR monoclonal antibodies bound to mfLEPR.MMHwith K_(D) values ranging from 5.18 nM to 264 nM, as shown in Table 8.

At 25° C., anti-LEPR monoclonal antibodies bound to hLEPR-mFc with K_(D)values ranging from 613 pM to 5.7 nM, as shown in Table 7. At 37° C.,anti-LEPR monoclonal antibodies bound to hLEPR-mFc with K_(D) valuesranging from 1.16 nM to 12.8 nM, as shown in Table 8.

None of the anti-LEPR monoclonal antibodies of the invention bound tomLEPR.MMH or rLEPR.MMH at 25° C. or at 37° C. (data not shown).

Example 4 Anti-LEPR Antibodies of the Invention Bind LEPR in thePresence of Leptin:LEPR Binding

Blocking of anti-LEPR antibodies from binding to LEPR by human Leptinwas evaluated using a real-time surface plasmon resonance biosensor on aBiacore T200 instrument. The entire study was performed in 10 mM HEPESpH 7.4, 150 mM NaCl, 3 mM EDTA, and 0.05% v/v Surfactant Tween-20(HBS-ET running buffer) at 25° C. The Biacore CM5 sensor surface wasfirst derivatized by amine coupling human Leptin (R&D Systems, #398-LP)using standard EDC/NHS surface chemistry. A complex of human LEPR andhuman Leptin, was formed by injecting 20 nM of human LEPR extracellulardomain expressed with a C-terminal myc-myc-hexahistidine tag (hLEPR-MMH;SEQ ID NO: 114), over the human Leptin immobilized Biacore sensorsurface at a flow rate of 10 μL/minute or 25 μL/minute for 4 minutes, toachieve a binding response of approximately 200 RU. To evaluate whetherantibody binding to hLEPR-MMH is blocked by human Leptin, 200 nM ofanti-LEPR monoclonal antibodies were injected over the preformedhLEPR-MMH:human Leptin complex, at a flow rate of 50 μL/minute or 25μL/minute for 4-5 minutes. All of the anti-LEPR antibodies of thisinvention that were tested bound to the complex of hLEPR-MMH and humanLeptin (“Leptn;LEPR”) with nearly similar signal strength and theobserved binding, expressed in RUs, are reported in Table 9. This resultindicates that human Leptin does not block the binding of hLEPR-MMH toanti-LEPR antibodies tested.

TABLE 9 Binding of anti-LEPR monoclonal antibodies to the pre-complex ofhLEPR-MMH and human Leptin. hLEPR-MMH 200 nM mAb Antibody Bound (RU)Bound (RU) H4H16650P2 196 81 H4H16679P2 195 90 H4H17319P2 196 92

Example 5 Human Leptin Receptor Blocking ELISA

For the ELISA, human Leptin (hLeptin; R&D Systems, #398-LP-01 M) wascoated at a concentration of 5 μg/mL in PBS on a 96-well microtiterplate overnight at 4° C. Nonspecific binding sites were subsequentlyblocked using a 0.5% (w/v) solution of BSA in PBS. A constant amount of10 nM of extracellular domain portion of LEPR protein that was expressedwith a C-terminal human Fc tag (hLEPR.hFc; SEQ ID NO: 116) was titratedwith anti-LEPR antibodies, hLeptin protein, or an isotype controlantibody ranging from 8.5 pM to 500 nM in serial dilution. Theseantibody-protein or protein-protein complexes were then incubated for1.5 hour at room temperature (RT). Complexes were subsequentlytransferred to microtiter plates coated with hLeptin and incubated for 2hours at RT, the wells were washed, and plate-bound hLEPR.hFc wasdetected with an anti-human IgG polyclonal antibody conjugated withhorseradish peroxidase (Jackson ImmunoResearch Inc, #109-035-098).Samples were developed with a TMB solution (BD Biosciences, #555214;substrate A and B mixed at 1:1 ratio as per manufacturer's instructions)to produce a colorimetric reaction and then neutralized with 1M sulfuricacid before measuring absorbance at 450 nm on a Victor X5 plate reader.

Data analysis was performed using a sigmoidal dose-response model withinPrismTM software (Graph Pad). Percent blockade at maximum concentrationof the antibody tested was calculated as an indicator of the ability ofthe antibodies to block the binding of 10 nM of hLEPR.hFc to humanLeptin on the plate. In the calculation, binding signal of 10 nM ofhLEPR.hFc without the presence of the antibody was referenced as 100%binding or 0% blocking; and the baseline signal of buffer alone withoutthe presence of hLEPR.hFc was referenced as 0% binding or 100% blockingThe blocking data at 500nM antibody concentration is summarized in Table10.

As shown in Table 10, none of the anti-LEPR antibodies of the inventiondemonstrated >28% blocking of the binding of hLEPR.hFc to the hLeptincoated surface. However, the Comparator Antibody and the hLeptin, as thepositive control, were able to block 99% of the hLEPR.hFc binding to thehLeptin coated surface. The isotype control antibody demonstrated nomeasurable blocking at concentrations up to 500 nM.

TABLE 10 ELISA blocking of hLEPR.hFc binding to hLeptin by anti-LEPRantibodies 500 nM Ab Blocking of 10 nM hLEPR.hFc Binding to hLeptinAntibody (% blockade) H4H18487P2 5 H4H18417P2 16 H4H18482P2 25H4H18492P2 −3 H4H18445P2 28 H4H18446P2 −5 H4H18449P2 8 H4H18438P2 15H4H16650P2 −7 H4H16679P2 7 H4H17319P2 9 H4H17321P2 6 Controls Isotypecontrol antibody −3 Human Leptin 99 Comparator Antibody 99 Mouse IgG2aIsotype control 32

Example 6 Cell Binding by FACS Analysis withHEK293/Mycx2-hLepR(ecto)-GPI Anchored Cells

Leptin receptor, LEPR, is a single-pass transmembrane receptor of theclass I cytokine receptor family (Tartaglia et al. (1997) J Biol Chem7:272(10):6093-6). LEPR can bind to Leptin, a protein predominantlyexpressed by adipose tissue that is involved in regulation of foodintake and metabolism (Friedman et al. (2014) J Endocrinol 223(1):T1-8).

In order to assess cell binding by anti-LEPR antibodies HEK293 stablecell lines were generated. One cell line, known hereafter asHEK293/hLEPR-GPI, stably expressed the extracellular domain of humanLEPR (amino acids 22-839 of accession #P48357 (SEQ ID NO:113), IsoformB) with an N-terminal myc-myc tag and C-terminal peptide sequence fromhuman carboxypeptidase M that guides the addition of GPI(Glycosylphosphatidylinositol) (Deddish et al. (1990) J. BiologicalChemistry 265:25:15083-89) such that the protein can be GPI-anchored tothe membrane. Another HEK293 cell line was generated to stably expressthe full length human LEPR (amino acids 1-1165 of accession #P48357(SEQID NO:113), Isoform B) along with a luciferase reporter(Stat3-luciferase, Stat3-luc, SA Bioscience, #CLS-6028L), and is knownhereafter as HEK293/Stat3-luc/hLEPR-FL. HEK293 cells with theStat3-luciferase reporter only (HEK293/Stat3-luc) were also generated asa control cell line.

For the FACS analysis, HEK293 parental cells and HEK293/hLEPR-GPI cellswere dissociated and plated onto 96-well v-bottom plates at 5×10⁵cells/well in PBS containing 2% FBS (FACS buffer). In order to testwhether the ability of anti-hLEPR antibodies to bind to cells isaffected by the presence of Leptin, FACS buffer with or without 1 μMhuman Leptin (R&D Systems, #398-LP) was incubated with the cells for 30minutes at 4° C., followed by the addition of anti-LEPR antibodies orcontrol antibodies at 10nM in FACS buffer. The cells were subsequentlyincubated for 30 minutes at 4° C., followed by washing and thenincubation with 16 μg/mL of Alexa Fluor®-647 conjugated secondaryantibody (Jackson ImmunoResearch Laboratories Inc., #109-547-003) for 30minutes at 4° C. Cells were subsequently fixed using BD CytoFix™ (BectonDickinson, #554655), filtered, and analyzed on a HyperCyt Flow Cytometer(Beckman Coulter). Unstained and secondary antibody alone controls werealso tested for all cell lines. The results were analyzed using ForeCyt(IntelliCyt) and FlowJo version 10 software to determine the geometricmeans of fluorescence for viable cells. The geometric mean offluorescence for each sample was then normalized to the geometric meanof unstained cells to obtain relative binding per condition referred toas “binding ratios”, and these binding ratios were recorded for eachantibody tested.

As shown in Table 11, 9 anti-LEPR antibodies of the invention tested at10 nM demonstrated binding to HEK293/hLEPR-GPI cells with binding ratiosranging from 824 to 3374 fold without Leptin. The anti-LEPR antibodiesalso bound in the presence of 1 μM Leptin with binding ratios of 398 and4184 fold. As shown in Table 11, he Comparator Antibody tested at 10 nMdemonstrated binding to HEK293/hLEPR-GPI cells with a binding ratio of2349-fold without Leptin but showed significantly less binding to cellsin the presence of 1 μM Leptin with binding ratio of 112. The anti-LEPRantibodies did not demonstrate any significant binding to the HEK293parental cells with binding ratios with and without 1 μM Leptin rangingfrom 1 to 9 fold. The isotype control antibodies and secondaryantibodies alone samples also did not demonstrate significant binding toeither cell line with or without Leptin, with binding ratios rangingfrom 1 to 6 fold.

As shown in Table 12, four antibodies of the invention tested at 70 nMwithout Leptin, demonstrated binding to HEK293/hLEPR-GPI cells withbinding ratios ranging from 707 to 1131 fold and toHEK293/Stat3-luc/hLEPR-FL cells with binding ratios ranging from 42 to51. The anti-LEPR antibodies did not demonstrate any significant bindingto the HEK293/Stat3-luc cells with binding ratios ranging from 1 to 8fold. The isotype control antibodies and secondary antibodies alonesamples also did not demonstrate significant binding to any of the celllines tested, with binding ratios ranging from 1 to 2 fold.

TABLE 11 Binding of 10 nM anti-LEPR antibodies to HEK293/hLEPR-GPI andHEK293 parental cells +/−1 μM Human Leptin Binding Ratio: Normalized toUnstained Sample of Each Cell Line No added Leptin 1 μM Leptin HEK293HEK293/ HEK293 HEK293/ Antibody parental hLEPR-GPI parental hLEPR-GPIAntibody Type H4H16650P2 5 2420 4 3124 Agonist H4H16679P2 5 2058 8 2223Agonist H4H18417P2 1 1835 2 2604 Potentiator H4H18438P2 2 1486 3 2414Potentiator H4H18445P2 2 2016 3 2488 Potentiator H4H18449P2 5 3374 93113 Potentiator H4H18482P2 1 1966 3 2704 Potentiator H4H18487P2 1 24223 2670 Potentiator H4H18492P2 3 2603 7 4184 Potentiator Comparitor 62349 3 112 N/A Isotype control 1 6 2 4 N/A antibody Secondary antibody 13 2 3 N/A alone Unstained 1 1 1 1 N/A *Classification of antibodies as“Agonist” or “Potentiator” is based in part on the results observed inExamples 7 and 8 herein.

TABLE 12 Binding of 70 nM anti-LEPR antibodies to HEK293/hLEPR-GPI,HEK293/Stat3-hLEPR-FL, and HEK293/Stat3-luc parental cells BindingRatio: Normalized to Unstained Sample of Each Cell Line HEK293/ HEK293/HEK293/ Stat3-luc Antibody Stat3-luc hLEPR-GPI hLEPR-FL Antibody TypeH4H16650P2 6 707 42 Agonist H4H16679P2 8 1078 51 Agonist H4H17319P2 71131 47 Agonist H4H17321P2 7 1126 46 Agonist Isotype control 2 2 2antibody Secondary 1 1 1 antibody alone Unstained 1 1 1

Example 7 Anti-LEPR Antibodies of the Invention Activate LEPR Signalingin the Presence or Absence of Leptin

A bioassay was developed to detect the transcriptional activation ofSTAT3 via LEPR activation using a reporter cell line that stablyexpresses full-length human LEPR (hLEPR; amino acids 1 through 1165 ofaccession number NP_002294.2) along with a luciferase reporter(STAT3-Luc; Qiagen, #CLS-6028L) in an IMR-32 cell line, a humanneuroblastoma cell line. The resulting stable cell line, referred to asIMR-32/STAT3-Luc/hLEPR, was isolated and maintained in MEM-Earl mediumsupplemented with 10% FBS, NEAA, 1 ug/mL Puromycin, 100 ug/mL ofHygromycin B and Penicillin/Streptomycin/L-Glutamine (Complete Medium).

The resulting bioassay was used to measure the effect of anti-LEPRantibodies of the invention on LEPR signaling in the presence or absenceof Leptin. For the bioassay, IMR-32/STAT3-Luc/hLEPR cells were plated atthe density of 20,000 cells/100 ul/well for 96 well format in thecomplete medium, and the following day replaced with the appropriatevolume of Opti-MEM medium supplemented with 1% BSA and 0.1% FBS (AssayBuffer) for 30 minutes. To measure the effect of the antibodies of theinvention in the absence of Leptin, the anti-LEPR antibodies or anisotype control antibody and human Leptin (hLeptin; R&D Systems,#398-LP) were half-log serially diluted to final concentrations rangingfrom 100 nM to 300 fM in Assay Buffer, which were added to the cells andsubsequently incubated overnight at 37° C. in 5% CO2.

To measure the effect of the antibodies of the invention in the presenceof Leptin, a fixed concentration of human Leptin at 200 pM in AssayBuffer was added to the cells, immediately followed by the addition ofanti-LEPR antibodies or isotype control antibody that were half-logserially diluted to final concentrations ranging from 100 nM to 300 fM.The samples were then incubated overnight at 37° C. in 5% CO2. OneGloreagent (Promega, #E6051) was then added to the samples and luciferaseactivity was measured on an Envision Multilable Plate Reader (PerkinElmer) in Luminescent mode. The relative light unit (RLU) values wereobtained and the results were analyzed using nonlinear regression withGraphPad Prism software (GraphPad). The maximum RLU value obtained fromthe hLeptin dose response was defined as 100% activation in theIMR-32/STAT3-Luc/hLEPR assay.

As shown in Table 13, in Study 1, in the absence of hLeptin, all of theanti-LEPR antibodies tested demonstrated weak stimulation of theIMR-32/STAT3-Luc/hLEPR cells with EC₅₀ values ranging from 134 pM to11.9 nM and maximal activation ranging from 5% to 13% respectively thatof maximum activation obtained from the hLeptin dose response. In Study2, in the absence of hLeptin, the 4 anti-LEPR antibodies testeddemonstrated stimulation of the IMR-32/STAT3-Luc/hLEPR cells with EC₅₀values ranging from 61.9 pM to 206.9 pM and maximal activation rangingfrom 65% to 68% respective to the maximum activation obtained from thehLeptin dose response. In Study 1, in the presence of 200 pM of hLeptin,all of the anti-LEPR antibodies tested demonstrated stimulation of theIMR-32/STAT3-Luc/hLEPR cells with EC₅₀ values ranging from 20.2 pM to523 pM and maximal activation ranging from 66% to 107% respectively thatof maximum activation obtained from the hLeptin dose response. Becausethese antibodies enhanced leptin-induced LEPR signaling, theseantibodies were classified as “potentiators”, as defined herein. InStudy 2, in the presence of 200 pM of hLeptin, the 4 anti-LEPRantibodies tested demonstrated stimulation of the IMR-32/STAT3-Luc/hLEPRcells with EC₅₀ values ranging from 51.9 pM to 257.3 pM with maximalactivation ranging from 76% to 88% that of maximum activation obtainedfrom the hLeptin dose response. LEPR signaling was not appreciablyenhanced by these antibodies in the presence of leptin. The isotypecontrol antibody did not demonstrate any measurable stimulation of theIMR-32/STAT3-Luc/hLEPR cells in any of the assays.

TABLE 13 Activation of hLEPR by anti-LEPR Antibodies IMR-32/LEPRIMR-32/LEPR without with 200 pM human Leptin human Leptin % % AntibodyEC₅₀ (M) activation EC₅₀ (M) activation Study 1 H4H18445P2 1.19E−08 54.10E−10 97 H4H18446P2 3.73E−10 6 3.42E−11 68 H4H18449P2 2.12E−10 135.23E−11 66 H4H18438P2 1.49E−09 5 2.02E−11 76 H4H18482P2 2.69E−10 71.69E−10 94 H4H18487P2 8.01E−10 6 4.10E−10 107 H4H18492P2 1.34E−10 52.74E−11 94 H4H18417P2 1.53E−10 5 5.23E−10 87 Study 2 H4H16650P26.19E−11 68 5.19E−11 88 H4H16679P2 8.62E−11 65 7.37E−11 88 H4H17319P21.867E−10  68 1.914E−10  76 H4H17321P2 2.069E−10  66 2.573E−10  76

Example 8 Anti-LEPR Antibodies of the Invention Activate Signaling inCells Expressing Signaling-Defective or Signaling-Impaired LEPR Mutants

LEPR mutants have been identified that exhibit defective or impairedleptin-mediated signaling and are associated with early-onset obesity.For example, LEPR-A409E is a signaling-defective mutant LEPR proteinthat does not transduce leptin signals to STAT3; the A409E mutant wasoriginally identified as a monogenic cause of early onset obesity.(Farooqi et al., 2007, N Engl J Med 356(3): 237-247). LEPR-P316T is asignaling-impaired mutant LEPR protein that has also been shown to beassociated with early-onset obesity. (Mazen et al., 2011, Mol GenetMetab 102:461-464).

In this Example, the ability of anti-LEPR antibodies of the invention tostimulate LEPR signaling in cell lines expressing signaling-defective orsignaling-impaired LEPR mutants was assessed. In particular, reportercell lines (HEK293) were constructed expressing either wild-type LEPR,LEPR-A409E (signaling-defective) or LEPR-P316T (signaling-impaired).Cells were treated with either vehicle only, recombinant human leptin,control IgG, or agonist anti-LEPR antibodies of the present invention(H4H16650 or H4H16679), and the extent of LEPR signaling (as measured byWestern blot detection of pSTAT3-Y705 expression relative to STAT3expression) was determined.

The agonist anti-LEPR antibodies of the present invention (H4H16650 andH4H16679) were shown in these experiments to stimulate LEPR signaling incells expressing the LEPR-A409E mutant or the LEPR-P316T mutant (asmeasured by STAT3 expression) in a dose-dependent manner (FIG. 2, panelsB and C). By contrast, leptin treatment induced only modest signaling incells expressing the LEPR-P316T mutant, and no signaling in cellsexpressing the LEPR-A409E mutant. (FIG. 2, panel A). Moreover, no LEPRsignaling was detected in any of the cell lines treated with vehicle orIgG control antibody (data not shown). Other signaling-defective orsignaling-impaired LEPR mutants were tested in this assay but were notactivated by anti-LEPR mutants (data not shown), suggesting that thisrescue effect may be mutant-dependent.

The results of this Example indicate that the agonist anti-LEPRantibodies of the present invention may be useful in the treatment ofdiseases and disorders (e.g., early-onset obesity) that are caused by orassociated with certain signaling-defective or signaling-impaired LEPRmutants (e.g., LEPR-P316T or LEPR-A409E).

Example 9 Octet Cross-Competition between Different Anti-LEPR MonoclonalAntibodies

Binding competition between a panel of different anti-LEPR monoclonalantibodies was determined using a real time, label-free bio-layerinterferometry assay on the Octet HTX biosensor platform (Pall ForteBioCorp.). The entire experiment was performed at 25° C. in buffercontaining 10 mM HEPES, 150 mM NaCl, 3 mM EDTA, and 0.05% v/v SurfactantTween-20, 1 mg/mL BSA, pH7.4 (HBS-EBT) with the plate shaking at thespeed of 1000 rpm. To assess whether two antibodies were able to competewith one another for binding to their respective epitopes on recombinanthuman LEPR expressed with a C-terminal myc-myc-hexahistidine tag(hLEPR.mmh; SEQ ID NO: 114), around 0.25 nm or 0.34 nm of hLEPR-MMH wasfirst captured onto anti-penta-His antibody coated Octet biosensor tips(Fortebio Inc, #18-5122) by submerging the biosensor tips for 5 minutesin wells containing 20 μg/mL of hLEPR-MMH. The antigen capturedbiosensor tips were then saturated with a first anti-LEPR monoclonalantibody (subsequently referred to as mAb-1) by dipping into wellscontaining 50 μg/mL solution of mAb-1 for 210 seconds. The biosensortips were then subsequently dipped into wells containing a 50 μg/mLsolution of a second anti-LEPR monoclonal antibody (subsequentlyreferred to as mAb-2) for 150 seconds. The biosensor tips were washed inHBS-EBT buffer in between every step of the experiment. The real-timebinding response was monitored during the entire course of theexperiment and the binding response at the end of every step wasrecorded. The response of mAb-2 binding to hLEPR-MMH pre-complexed withmAb-1 was compared and competitive/non-competitive behavior of differentanti-LEPR monoclonal antibodies was determined as shown in Table 14 andTable 15.

TABLE 14 Cross-competition between anti-LEPR monoclonal antibodies Firstantibody (mAb-1) binding to captured hLEPR- Second antibody (mAb-2)shown to MMH compete with mAb-1 H4H18492P2 H4H18417P2 H4H18438P2H4H18417P2 H4H18492P2 H4H18438P2 H4H18438P2 H4H18492P2 H4H18417P2H4H16650P2 H4H16679P2 H4H16679P2 H4H16650P2 H4H18445P2 H4H18482P2H4H18487P2 H4H18446P2 H4H18446P2 H4H18482P2 H4H18487P2 H4H18445P2H4H18482P2 H4H18445P2 H4H18487P2 H4H18487P2 H4H18445P2 H4H18482P2H4H18449P2 None Comparator Antibody None

TABLE 15 Cross-competition between anti-LEPR monoclonal antibodies mAb-2that competes with mAb-1 mAb-1 H4H17319P2 H4H17321P2 H4H16650P2H4H16679P2 H4H17321P2 H4H17319P2 H4H16650P2 H4H16679P2 H4H16650P2H4H17319P2 H4H17321P2 H4H16679P2 H4H16679P2 H4H17319P2 H4H17321P2H4H16650P2

Example 10 In Vivo Efficacy of LEPR Agonist Antibodies H4H16650P2,H4H16679P2, H4H17319P2 and H4H17321P2 in an Inducible Mouse Model ofLeptin Deficiency

The effects of four specific agonist anti-LEPR antibodies of theinvention, H4H16650P2, H4H16679P2, H4H17319P2, and H4H17321P2 on foodintake, body weight and adiposity were determined in an inducible modelof leptin deficiency in genetically engineered LEPR^(Hu/Hu) mice, thatexpress a leptin receptor which is composed of the human LEPR ectodomainsequence in place of the murine LEPR ectodomain sequence. The model ofleptin deficiency was induced by hydrodynamic DNA delivery (HDD) of aplasmid encoding an hFc-tagged mouse LEPR ectodomain (referred to hereinas mLEPR.hFc or “Leptin trap”; SEQ ID NO: 120). The Leptin trap whenexpressed is secreted and binds circulating Leptin. After HDD of 50 μgof the DNA construct encoding the Leptin trap, mice exhibited increasedfood consumption and increased adiposity and body weight.

Baseline daily food intake was measured between 7 and 4 days prior toadministration of the Leptin trap (days −7 and −4). On day 0,thirty-five 13- to 17-week old male LEPR^(Hu/Hu) mice were successfullysubjected to HDD with the Leptin trap. On days 6 and 13 post HDD,retro-orbital bleeds were collected and body composition includingadiposity was quantified by μCT. On day 7 post HDD, mice were randomizedinto five groups of 7 mice based on percent body weight change from day0. Each group received via subcutaneous injection either a single doseof isotype control antibody at 3 mg/kg, H4H16650P2 at 3 mg/kg,H4H16679P2 at 3 mg/kg, H4H17319P2 at 3 mg/kg, or H4H17321 at 3 mg/kg.The isotype control antibody did not bind any known mouse protein. Foodintake and body weight were measured for each animal for the duration ofthe study. FIG. 3 summarizes the average daily food intake for eachtreatment group. In FIG. 3, the dotted line represents the averagebaseline food intake prior to HDD injection. The percent change in bodyweight from day 0 was calculated for each animal at each time point.FIG. 4 summarizes the average percent change in body weight for animalsin each antibody treatment group. FIG. 5 summarizes the average fat massfor animals in each antibody treatment group quantified by μCT 1 dayprior to and 6 days following antibody treatment. All results areexpressed as mean±SEM.

As shown in FIGS. 3 and 4, following HDD with the Leptin trap, similarincreases in food intake and percent change in body weight were observedamong the groups of mice before antibody treatment. As shown in FIG. 3,mice treated with antibodies H4H16650P2 or H4H16679P2 at 3 mg/kgexhibited significant reductions in food intake starting at one dayafter antibody treatment (day 8 post HDD) and at subsequent time pointsmeasured as compared to mice injected with the isotype control antibody.Mice treated with antibodies H4H17319P2 or H4H17321P2 at 3 mg/kgexhibited a significant reduction in food intake at two days postantibody treatment (day 9 post HDD) and at the other subsequent timepoints measured as compared to mice injected with isotype controlantibody. As shown in FIG. 4, mice treated with antibody H4H16650P2 at 3mg/kg exhibited a significant reduction in percent body weight changeone day after antibody treatment (day 8 post HDD) and at othersubsequent time points measured as compared to mice injected withisotype control antibody. One day after antibody treatment, on day 8,mice treated with the isotype control showed a 21.16±1.27% increase inbody weight from day 0, whereas mice treated with H4H16650P2 had a15.57±0.9% increase in body weight from day 0. Mice treated withantibodies H4H16679P2, H4H17319P2 or H4H17321P2 at 3 mg/kg exhibited asignificant reduction in percent body weight change two days afterantibody treatment (day 9 post HDD) and at other subsequent time pointsmeasured as compared to mice injected with isotype control antibody. Onday 9, the % body weight changes from day 0 were 23.18±1.22, 13.17±1.05,12.95±1.26, 15.98±1.78 and 15.83±2.01 for mice treated with isotypecontrol, H4H16650P2, H4H16679P2, H4H17319P2, or H4H17321P2,respectively. As shown in FIG. 5, mice treated with isotype controlantibody at 3 mg/kg demonstrated a significant increase in fat mass 6days after antibody treatment (day 13 post HDD) as compared to 1 dayprior to antibody treatment (day 6 post HDD). Mice treated withantibodies H4H16650P2, H4H16679P2, H4H17319P2, or H4H17321P2 at 3 mg/kgdid not gain adipose mass after antibody treatment as compared topre-antibody treatment. After 6 days of treatment (day 13 post HDD),mice treated with antibodies H4H16650P2, H4H16679P2 or H4H17319P2 at 3mg/kg demonstrated significant decreases in fat mass as compared to micetreated with isotype control antibody at 3 mg/kg.

Example 11 Epitope Mapping of H4H16650P2 Binding to Human LeptinReceptor (hLEPR.mmh) by Hydrogen Deuterium Exchange

Experiments were conducted to determine the amino acid residues ofhLEPR.mmh (amino acids M1-D839 of SEQ ID NO: 114) with which H4H16650P2interacts. For this purpose H/D exchange epitope mapping with massspectrometry was carried out. A general description of the H/D exchangemethod is set forth in, e.g., Ehring (1999) Analytical Biochemistry267(2):252-259; and Engen and Smith (2001) Anal. Chem. 73:256A-265A.

Experimental procedure. HDX-MS experiments were performed on anintegrated Waters HDX/MS platform, consisting of a Leaptec HDX PALsystem for the deuterium labeling, a Waters Acquity M-Class (Auxiliarysolvent manager) for the sample digestion and loading, a Waters AcquityM-Class (pBinary solvent manager) for the analytical column gradient,and Synapt G2-Si mass spectrometer for peptic peptide mass measurement.

The labeling solution was prepared in 10 mM PBS buffer in D2O at pD 7.0(equivalent to pH 6.6). For deterium labeling, 3.8 μL of hLEPR.mmh (8pmol/μL) or hLEPR.mmh premixed with the antibody in 2:1 molar ratio wasincubated with 56.2 μL D20 labeling solution for various time-points(e.g., undeuterated control=0 sec, labeled for 1 min and 20 min). Thedeuteration was quenched by transferring 50 μL sample to 50 μLpre-chilled quench buffer (0.2 M TCEP, 6 M guanidine chloride in 100 mMphosphate buffer, pH 2.5) and the mixed sample was incubated at 1.0° C.for two minutes. The quenched sample was then injected into a Waters HDXManager for online pepsin/protease XIII digestion. The digested peptideswere trapped onto an ACQUITY UPLC BEH C18 1.7-μm, 2.1×5 mm VanGuardpre-column at 0° C. and eluted to an analytical column ACQUITY UPLC BEHC18 1.7-μm, 1.0×50 mm for a 9-minute gradient separation of 5%-40% B(mobile phase A: 0.1% formic acid in water, mobile phase B: 0.1% formicacid in acetonitrile). The mass spectrometer was set at cone voltage of37 V, scan time of 0.5 s, and mass/charge range of 50-1700 Th.

For the identification of the peptides from human LEPR, LC-MSE data fromundeuterated sample were processed and searched against the databaseincluding human LEPR, pepsin, and their randomized sequences via WatersProteinLynx Global Server (PLGS) software. The identified peptides wereimported to DynamX software and filtered by two criteria: 1) minimumproducts per amino acid: 0.2, and 2) replication file threshold: 3.DynamX software then automatically determined deuterium uptake of eachpeptide based on retention time and high mass accuracy (<10 ppm) acrossmultiple time points with 3 replicates at each time.

Results. Using the online pepsin/protease XIII column coupled withMS^(E) data acquisition, total 201 peptides from human LEPR werereproducibly identified in the absence or presence of the antibody,representing 70% sequence coverage. Five peptides had significantlyreduced deuteration uptake (centroid delta values>0.4 daltons withp-values<0.05) when bound to H4H16650P2 as shown in the Table 16. Therecorded peptide mass corresponds to the average value of the centroidMH+ mass from three replicates. These peptides, corresponding to aminoacids 162-169 (amino acids LYVLPEVL of human LEPR; SEQ ID NO: 113), andto amino acids 170-181 (amino acids EDSPLVPQKGSF of human LEPR; SEQ IDNO: 113), had a slower deuteration rate when bound to H4H16650P2. Theseidentified residues also correspond to residues acids 162-169 and170-181 of human LEPR as defined by Uniprot entry P48357 (SEQ ID NO.113; Human leptin receptor)

TABLE 16 Human Leptin receptor peptides with significant protection uponbinding to antibody H4H16650P2 1 min Deuteration 20 min DeuterationhLEPR.mmh + hLEPR.mmh + Residues hLEPR.mmh H4H16650P2 Δ hLEPR.mmhH4H16650P2 Δ 162-169 949.03 ± 0.03 947.99 ± 0.02 −1.04 949.23 ± 0.02948.16 ± 0.02 −1.03 163-169 835.82 ± 0.03 834.79 ± 0.02 −1.03 836.03 ±0.02 834.94 ± 0.02 −1.08 170-181 1310.02 ± 0.05  1309.12 ± 0.03  −0.891309.77 ± 0.02  1309.38 ± 0.02  −0.39

Example 12 In Vivo Efficacy Testing of LEPR Potentiator Antibodies inHumanized LEPR Mice

The effects of three specific potentiator anti-LEPR antibodies of theinvention, H4H18482P2, H4H18487P2 and H4H18492P2, on body weight andadiposity were determined in singly-housed genetically engineeredLEPR^(Hu/Hu) mice, that express a leptin receptor which is composed ofthe human LEPR ectodomain sequence in place of the murine LEPRectodomain sequence (mLEPR.hFc, SEQ ID NO: 120).

On days −19 body composition including adiposity was quantified by μCT.On days 0, forty-eight 14 to 16-week old female LEPR^(Hu/Hu) mice wererandomized to four groups of 12 mice based on body weight. On days 0 and11, mice from each group received via subcutaneous injection a singledose of isotype control antibody at 30 mg/kg, H4H18482P2 at 30 mg/kg,H4H18487P2 at 30 mg/kg or H4H18492P2 at 30 mg/kg. The isotype controlantibody does not bind any known mouse protein. Body weight was measuredfor the duration of the study for each animal. The percent change inbody weight from day 0 was calculated for each animal at each timepoint. FIG. 6 summarizes the average percent change in body weight foranimals in each treatment group. FIG. 6 summarizes the average fat massfor animals in each antibody treatment group quantified by μCT 19 daysprior to and 11 days following antibody treatment. All results areexpressed as mean±SEM.

As shown in FIG. 6, decreases in percent change in body weight wereobserved following dosing with the LEPR potentiator antibodies, but notthe isotype control antibody. As shown in FIG. 6, mice treated withH4H18482P2 at 30 mg/kg exhibited significant decreases in percent bodyweight change starting two days after treatment (day 2), and at theother time points compared to mice injected with an isotype controlantibody. Mice treated with H4H18487P2 at 30 mg/kg exhibited significantdecreases in percent body weight change starting at day 2 and at theother time points compared to mice injected with isotype controlantibody. Mice treated with H4H18492P2 at 30 mg/kg exhibited asignificant reduction in percent body weight change on days 4, 5 and 17but not at other time points compared to mice injected with isotypecontrol antibody. Mice treated with H4H18482P2 at 30 mg/kg exhibited asignificant decrease in percent body weight change starting at day 6 andon subsequent days but not days 7, 14 and 17, compared to mice injectedwith H4H18492P2. Mice treated with H4H18487P2 at 30 mg/kg exhibited asignificant decrease in percent body weight change starting at day 3 andat the other time points, but not days 4 and 5, compared to miceinjected with H4H18492P2.

As shown in FIG. 7A, there were no differences in fat mass between thegroups prior to treatment (day −19). As shown in FIG. 7B, mice treatedwith antibodies H4H18482 and H4H18487, but not H4H18492, at 30 mg/kgshowed a statistically significant decrease in fat mass 17 days aftertreatment (day 12) as compared to the isotype control antibody.

The present invention is not to be limited in scope by the specificembodiments described herein. Indeed, various modifications of theinvention in addition to those described herein will become apparent tothose skilled in the art from the foregoing description and theaccompanying figures. Such modifications are intended to fall within thescope of the appended claims.

Example 13 Effect of Anti-LEPR Antibodies of the Invention on MonkeyLEPR Signaling

In order to assess transcriptional activation of monkey Leptin receptor,a stable cell line was developed. IMR-32 cells (human NeuroblastomaATCC) were generated to stably express the extracellular domain ofMacaca fascicularis LEPR (MfLEPR; amino acids 22 through 837 ofaccession number XP_005543194.1 with threonine at 827 changed toalanine) fused with the transmembrane and cytosolic domains of humanLEPR (hLEPR; amino acids 840 through 1165 of accession numberNP_002294.2) along with a luciferase reporter (STAT3-Luc; SABiosciences,#CLS-6028L). The resulting cell line, referred to hereafter asIMR-32/STAT3-Luc/MfLEPR was isolated and maintained in MEM-Earl mediumsupplemented with 10% FBS, NEAA, 1 ug/mL Puromycin, 100 ug/mL ofHygromycin B and Penicillin/Streptomycin/L-Glutamine.

The bioassay was performed to measure the effect of anti-LEPR antibodiesof the invention on monkey LEPR signaling in the absence of Leptin. Forthe bioassay, IMR-32/STAT3-Luc/MfLEPR cells were plated at 10,000cells/well in a 96-well plate in 0.1% FBS in Optimem withpenicillin/streptomycin (assay buffer) and incubated overnight at 37° C.in 5% CO₂. The following day human leptin (hLeptin), anti-LEPRantibodies or an isotype control antibody were serially diluted from 50nM to 0.8 pM in the assay buffer (plus a sample containing buffer alonewithout test molecule) and added to the cells. After 5.5 hours at 37° C.in 5% CO₂, luciferase activity was measured with OneGlo™ reagent(Promega, #E6031) and VictorTM X multilabel plate reader (Perkin Elmer).The results were analyzed using nonlinear regression (4-parameterlogistics) with Prism™6 software (Graph Pad) to obtain EC₅₀ values.Percentage of activation of antibodies was calculated as the maximumrange of RLU achieved by the antibody relative to that of maximum rangeof RLU achieved by hLeptin.

As shown in Table 17, in the absence of hLeptin, all of the anti-LEPRantibodies tested showed activation of monkey LEPR signaling inIMR-32/STAT3-Luc/mfLEPR cells with EC₅₀ values ranging from 266 pM to368 pM and maximal activation ranging from 76% to 82% where 100%activation was obtained with hLeptin. hLeptin activated with an EC₅₀value of 333 pM. The isotype control antibody did not demonstrate anymeasurable stimulation of the IMR-32/STAT3-Luc/mfLEPR cells.

TABLE 17 Activation of Macaca fascicularis LEPR by anti-LEPR antibodies% Leptin or Antibody EC₅₀ (M) Activation Human Leptin 3.33E−11 100H4H16650P2 2.66E−10 82 H4H16679P2 2.49E−10 80 H4H17319P2 3.65E−10 76H4H17321P2 3.68E−10 78 Isotype control antibody No Activation NoActivation

Example 14 Epitope Binding to the Full-Length Extracellular Domain ofHuman LEPR Using Luminex MFI Signal

To determine the epitope of human LEPR on which anti-LEPR antibodies ofthe invention bind, a Luminex FLEXMAP (FM3DD, LuminexCorp) flowcytometry based analysis was utilized to characterize the interaction ofanti-LEPR antibodies with recombinant human LEPR protein domains. Forthe assay, approximately 3 million carboxylated Microplex^(R)microspheres (Luminex, Cat #LC1000A), were washed, vortexed andsonicated in 0.1 M NaPO₄, pH 6.2 (activation buffer) and thencentrifuged to remove the supernatant. The microspheres were resuspendedin 120 μL of activation buffer and the carboxylate groups (—COOH) wereactivated by addition of 15 μL of 50 mg/mL of N-hydroxysuccinimide (NHS,Thermo Scientific, Cat #24500) followed by addition of 15 μL of 50 mg/mLof 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide (EDC, ThermoScientific,Cat #22980) at 25° C. After 10 minutes, the pH of the reaction wasreduced to 5.0 with the addition of 600 μL of 50 mM MES, pH 5 (couplingbuffer), and the microspheres were vortexed, and centrifuged to removesupernatant. The activated beads were immediately mixed with 500 μL of20 μg/mL monoclonal anti-myc antibodies with either a mouse IgG or ahuman IgG, in coupling buffer and incubated for two hours at 25° C. Thecoupling reaction was quenched by addition of 50 μL of 1M Tris-HCl, pH8.0 and the microspheres were rapidly vortexed, centrifuged, and washedfour times with 1 mL of DPBS, to remove uncoupled proteins and otherreaction components.

The transiently expressed LEPR proteins, including human LEPRextracellular domain expressed with a C-terminal myc-myc hexahistidinetag (human LEPR-MMH, SEQ ID NO: 113), human LEPR CRH1 (D1) expressedwith a C-terminal myc-myc hexahistidine tag (human LEPR CRH1 (D1)-MMH,amino acids 1-208 of SEQ ID NO: 113 with a myc-myc hexahistidine tag,amino acids 209-236), human LEPR CRH1 (D1,D2) domain expressed with aC-terminal myc-myc hexahistidine tag (human LEPR CRH1 (D1,D2)-MMH, aminoacids 1-318 of SEQ ID NO: 113 with a myc-myc hexahistidine tag, aminoacids 319-346), human LEPR CRH1-Ig (D1,D2,D3) domain expressed with aC-terminal myc-myc hexahistidine tag (human LEPR CRH1 (D1,D2,D3)-MMH,amino acids 1-278 of SEQ ID NO: 113 with a myc-myc hexahistidine tag,amino acids 279-306), human LEPR CRH1-Ig (D2,D3) domain expressed with aC-terminal myc-myc hexahistidine tag (human LEPR CRH1-Ig (D2,D3)-MMH,amino acids 1-198 of SEQ ID NO: 113 with a myc-myc hexahistidine tag,amino acids 199-226), human LEPR Ig (D3) domain expressed with aC-terminal myc-myc hexahistidine tag (human LEPR Ig (D3)-MMH, aminoacids 1-88 of SEQ iD NO: 113 with a myc-myc hexahistidine tag, aminoacids 89-116), human LEPR CRH2 domain expressed with a C-terminalmyc-myc hexahistidine tag (human LEPR CRH2-MMH, amino acids 1-207 of SEQID NO: 113 with a myc-myc-hexahistidine tag, amino acids 208-235), humanLEPR FNIII domain expressed with a C-terminal myc-myc hexahistidine tag(human LEPR FNIII-MMH, amino acids 1-204 of SEQ ID NO: 113 with amyc-myc hexahistidine tage, amino acids 205-232), and human LEPRIg-CRH2-FNIII domain expressed with a C-terminal myc-myc hexahistidinetag (human LEPR Ig-CRH2-FNIII-MMH, amino acids 1-510 of SEQ ID NO: 113with a myc-myc-hexahistidine tag, amino acids 511-538), were suspendedin serum free CHO-S-SFM II Medium (Thermo Fisher, Cat #31033020) andwere then clarified by centrifugation. Aliquots of microspheres withimmobilized anti-myc monoclonal antibodies, prepared as described above,were added individually to 1 mL of the each of these proteinsupernatants. The microspheres were gently mixed, incubated for twohours at 25° C., washed twice with 1 mL of DBPS, centrifuged to removethe supernatant and finally resuspended in 1 mL of DPBS buffer. Fortyeight μL of anti-myc IgG coupled microspheres from individual reactionswith full length human LEPR and with each of the human LEPR domainproteins were withdrawn and mixed together in 3.6 mL of PBS+20mg/mLBSA+0.05% sodium azide (blocking buffer).

From this mixed pool, 75 μL of microspheres were plated per well on a 96well filter plate (Millipore, Cat. No: MSBVN1250) and mixed with 25 μLof individual anti-human LEPR monoclonal antibodies (0.5 or 5 μg/mL),incubated for two hours at 25° C. and then washed twice with 200 μL ofDPBS with 0.05% Tween 20 (washing buffer). To detect and quantify theamounts of bound anti-LEPR antibody levels to individual microspheres,either 100 μL of 2.5 μg/mL R-Phycoerythrin conjugated goat F(ab′)2anti-human kappa (Southern Biotech, Cat #2063-09) in blocking buffer or100 μL of 1.25 μg/mL R-Phycoerythrin AffiniPure F(ab′)2 Fragment GoatAnti-Mouse IgG, F(ab′)2 Fragment Specific (Jackson lmmunoresearch, Cat.No: 115-116-072) in blocking buffer, was added and incubated for 30minutes at 25° C. After 30 minutes, the samples were washed twice with200 of washing buffer and resuspended in 150 μL of wash buffer. TheMedian Fluorescence intensity (MFI) of the microspheres was measured ina Luminex Analyzer.

TABLE 18 Luminex MFI signal of anti-LEPR antibodies binding to myc tagcaptured full-length extracellular domain of human LEPR and isonaltedhuman LEPR domains Ig- Full Length CRH1 CRH1 CRH1-Ig CRH1-Ig Ig CRH2-extracellular Probable Antibody (D1) (D1, D2) (D1, D2, D3) (D2, D3) (D3)CRH2 FNIII FNIII domain Binding site H4H18445P2 12 30 22 40 19 17 23014544 6573 FNIII H4H18446P2 17 682 205 645 25 65 32 16852 10536 Ig-CRH2-FNIII H4H18482P2 13 40 21 52 27 23 167 15316 7311 Ig-CRH2- FNIIIH4H18487P2 12 51 29 62 22 27 174 16320 7329 Ig-CRH2- FNIII H4H18417P2 1016048 3334 5502 17 39 14 37 4887 CRH1 D2 H4H18438P2 13 18931 6572 888430 165 25 468 6251 CRH1 D2 H4H18492P2 11 19371 6354 8685 19 18 16 1866382 CRH1 D2 H4H18449P2 20 2934 2056 42 24 15 13 43 7976 CRH1(D1-2)H4H16650P2 8 4722 2562 74 10 16 6 110 7603 CRH1(D1-2) H4H16679P2 12 43882797 34 14 33 10 42 7507 CRH1(D1-2) H4H17319P2 8 1246 938 14 8 91 20 83305 CRH1(D1-2) H4H17321P2 9 2649 1752 15 7 116 40 14 4696 CRH1(D1-2)Comparator −14 19 −57 27 10 9404 73 7112 3908 CRH2 mAb

The results of the Luminex based analysis are tabulated in Table 18.Luminex MFI signal intensities indicate that the twelve anti-LEPRantibodies of the invention bound to the complete human LEPRextracellular domain. Anti-LEPR antibodies H4H18417P2, H4H18438P2, andH4H18492P2, bound to epitopes within the CRH1 D2 domain of human LEPR.Anti-LEPR antibodies H4H18449P2, H4H16650P and H4H16679P, bound toepitopes within the CRH1(D1-2) domain of human LEPR. Anti-LEPR antibodyComparator mAB, bound to epitopes within the CRH2 domain of human LEPR.Anti-LEPR antibody H4H18445P2 bound to epitopes within the FNIII domainof human LEPR. Anti-LEPR antibodies H4H18446P2, H4H18482P2 andH4H18487P2, bound to epitopes within the Ig-CRH2-FNIII domain of humanLEPR.

What is claimed is:
 1. An isolated antibody or antigen-binding fragmentthereof that binds human leptin receptor (LEPR) and activates LEPRsignaling.
 2. The isolated antibody or antigen-binding fragment thereofof claim 1, wherein the antibody or antigen-binding fragment thereofexhibits one or more properties selected from the group consisting of:(i) binds monomeric human LEPR at 25° C. with a K_(D) of less than about150 nM as measured by surface plasmon resonance; (ii) binds monomerichuman LEPR at 25° C. with a t_(1/2) of greater than about 1 minute asmeasured by surface plasmon resonance; (iii) binds dimeric human LEPR at25° C. with a K_(D) of less than about 5 nM as measured by surfaceplasmon resonance; (iv) binds dimeric human LEPR at 25° C. with at_(1/2) of greater than about 15 minutes as measured by surface plasmonresonance; (v) binds human LEPR in complex with human leptin; (vi) doesnot block the LEPR:leptin interaction; (vii) binds cellsurface-expressed LEPR in the presence and absence of human leptin; and(viii) activates LEPR signaling with an EC₅₀ of less than about 90 pM ina cell-based reporter assay.
 3. The isolated antibody or antigen-bindingfragment thereof of claim 1, wherein the antibody or antigen-bindingfragment thereof activates LEPR signaling in a cell-based reporter assayat least 50% as effectively as leptin.
 4. The isolated antibody orantigen-binding fragment thereof of claim 3, wherein the antibody orantigen-binding fragment thereof activates LEPR signaling in acell-based reporter assay at least 70% as effectively as leptin.
 5. Anisolated antibody or antigen-binding fragment thereof that binds humanleptin receptor (LEPR), wherein the antibody or antigen-binding fragmentthereof comprises: (a) the complementarity determining regions (CDRs) ofa heavy chain variable region (HCVR) comprising the amino acid sequenceof SEQ ID NO:2, SEQ ID NO:18, SEQ ID NO: 26, SEQ ID NO: 34, SEQ ID NO:42, SEQ ID NO: 50, SEQ ID NO: 58, SEQ ID NO: 74, or SEQ ID NO: 82 and(b) the CDRs of a light chain variable region (LCVR) comprising theamino acid sequence of SEQ ID NO:10 or SEQ ID NO:66.
 6. The isolatedantibody or antigen-binding fragment thereof of claim 5, wherein theantibody or antigen-binding fragment comprises the heavy and light chainCDRs of an HCVR/LCVR amino acid sequence pair selected from the groupconsisting of SEQ ID NOs: 2/10,18/10, 26/10, 34/10, 42/10, 50/10, 58/66,74/66 and 82/66.
 7. The isolated antibody or antigen-binding fragmentthereof of claim 5, wherein the antibody or antigen-binding fragmentthereof comprises an HCVR/LCVR amino acid sequence pair selected fromthe group consisting of SEQ ID NOs: 2/10, 18/10, 26/10, 34/10, 42/10,50/10, 58/66, 74/66 and 82/66.
 8. The isolated antibody orantigen-binding fragment thereof of claim 7, wherein the antibody orantigen-binding fragment thereof activates LEPR signaling.
 9. Theantibody or antigen-binding fragment thereof of claim 1, wherein theantibody or antigen-binding fragment thereof competes for binding toLEPR with a reference antibody comprising an HCVR/LCVR amino acidsequence pair selected from the group consisting of SEQ ID NOs: 2/10,18/10, 26/10, 34/10, 42/10, 50/10, 58/66, 74/66 and 82/66.
 10. Theantibody or antigen-binding fragment thereof of claim 1, wherein theantibody or antigen-binding fragment thereof binds to the same epitopeon LEPR as a reference antibody comprising an HCVR/LCVR amino acidsequence pair selected from the group consisting of SEQ ID NOs:2/10,18/10, 26/10, 34/10, 42/10, 50/10, 58/66, 74/66 and 82/66.
 11. Apharmaceutical composition comprising the antibody or antigen-bindingfragment thereof of claim 1, and a pharmaceutically acceptable carrieror diluent.
 12. A method for treating a disease or condition associatedwith or caused by leptin deficiency or leptin resistance, the methodcomprising administering the pharmaceutical composition of claim 11 to asubject in need thereof.
 13. The method of claim 12, wherein the diseaseor condition associated with or caused by leptin deficiency or leptinresistance is selected from the group consisting of lipodystrophies,obesity, metabolic syndrome, diet-induced food craving, functionalhypothalamic amenorrhea, type 1 diabetes, type 2 diabetes, insulinresistance, severe insulin resistance due to mutation in insulinreceptor, Alzheimer's disease, leptin deficiency, leptin resistance,Leprechaunism/Donohue syndrome, and Rabson-Mendenhall syndrome.
 14. Amethod for treating a lipodystrophy condition in a patient, the methodcomprising administering the pharmaceutical composition of claim 11 to apatient in need thereof, wherein the lipodystrophy condition is selectedfrom the group consisting of congenital generalized lipodystrophy,acquired generalized lipodystrophy, familial partial lipodystrophy,acquired partial lipodystrophy, centrifugal abdominal lipodystrophy,lipoatrophia annularis, localized lipodystrophy, and HIV-associatedlipodystrophy.
 15. A method for treating a disease or conditionassociated with or caused by a signaling-defective or signaling-impairedLEPR mutation, the method comprising administering the pharmaceuticalcomposition of claim 11 to a subject in need thereof.
 16. The method ofclaim 15, wherein the signaling-defective or signaling-impaired LEPRmutation is LEPR-A409E or LEPR-P316T.
 17. The method of claim 15,wherein the disease or condition associated with or caused by asignaling-defective or signaling-impaired LEPR mutation is early-onsetobsesity.
 18. The method of claim 12, further comprising administering asecond therapeutic agent to the subject, wherein the second therapeuticagent is selected from the group consisting of a recombinant humanleptin, a PCSK9 inhibitor, a statin, ezetimibe, insulin, an insulinvariant, an insulin secretagogue, metformin, a sulfonylurea, a sodiumglucose cotransporter 2 (SGLT2) Inhibitor, a GLP-1 agonist/analogue, aglucagon (GCG) inhibitor, a glucagon receptor (GCGR) inhibitor, anangiopoietin-like protein (ANGPTL) inhibitor, Phentermine, Orlistat,Topiramate, Bupropion, Topiramate/Phentermine, Bupropion/Naltrexone,Bupropion/Zonisamide, Pramlintide/Metrelepin, Lorcaserin, Cetilistat,Tesofensine, and Velneperit.
 19. An isolated antibody or antigen-bindingfragment thereof that binds human leptin receptor (LEPR) and sensitizesLEPR to an antigen.
 20. The isolated antibody of claim 19 orantigen-binding fragment thereof that binds human leptin receptor(LEPR), wherein the antibody or antigen-binding fragment thereofcomprises: (a) the complementarity determining regions (CDRs) of a heavychain variable region (HCVR) comprising the amino acid sequence of SEQID NO: 26, SEQ ID NO: 34, SEQ ID NO: 42, SEQ ID NO: 50, SEQ ID NO: 58,SEQ ID NO: 74, or SEQ ID NO: 82 and (b) the CDRs of a light chainvariable region (LCVR) comprising the amino acid sequence of SEQ IDNO:10 or SEQ ID NO:66.
 21. The isolated antibody or antigen-bindingfragment thereof of claim 20, wherein the antibody or antigen-bindingfragment comprises the heavy and light chain CDRs of an HCVR/LCVR aminoacid sequence pair selected from the group consisting of SEQ ID NOs:26/10, 34/10, 42/10, 50/10, 58/66, 74/66 and 82/66.
 22. An isolatedantibody or antigen-binding fragment thereof that specifically bindshuman LEPR, wherein the antibody or antigen binding fragment interactswith amino acids 162-169 of SEQ ID NO: 113 and amino acids 170-181 ofSEQ ID NO: 113, as determined by hydrogen/deuterium exchange.
 23. Theisolated antibody or antigen-binding fragment of claim 22, wherein theantibody or antigen-binding fragment comprises HCDR1, HCDR2, HCDR3,LCDR1, LCDR2 and LCDR2 domains, respectively, selected from the groupconsisting of SEQ ID NOs: 4, 6 and 8 and SEQ ID NOs 12, 14 and
 16. 24.The isolated antibody or antigen-binding fragment of claim 22, whereinthe antibody or antigen-binding fragment comprises a HCVR/LCVR aminoacid sequence pair consisting of SEQ ID NOs: 2/10.